Lithium ion-based internal hybrid electrochemical energy storage cell

ABSTRACT

Provided is an internal hybrid electrochemical cell comprising: (A) a pseudocapacitance cathode comprising a cathode active material that contains a conductive carbon material and a porphyrin compound, wherein the porphyrin compound is bonded to or supported by the carbon material to form a redox pair for pseudocapacitance, wherein the carbon material is selected from activated carbon, activated carbon black, expanded graphite flakes, exfoliated graphite worms, carbon nanotube, carbon nanofiber, carbon fiber, a combination thereof; (B) a battery-like anode comprising lithium metal, lithium metal alloy, or a prelithiated anode active material (e.g. prelithiated Si, SiO, Sn, SnO 2 , etc.), and (C) a lithium-containing electrolyte in physical contact with the anode and the cathode; wherein the cathode active material has a specific surface area no less than 100 m 2 /g which is in direct physical contact with the electrolyte.

FIELD OF THE INVENTION

This invention relates generally to the field of electrochemical energystorage devices and, more particularly, to a fundamentally new internalhybrid battery/pseudocapacitor cell featuring a battery-like anode and apseudocapacitor-like cathode.

BACKGROUND OF THE INVENTION

Supercapacitors (Ultra-Capacitors or Electro-Chemical Capacitors):

A supercapacitor normally depends on porous carbon electrodes to createa large surface area conducive to the formation of diffuse electricdouble layer (EDL) charges. The ionic species (cations and anions) inthe EDL zones are formed in the electrolyte near an electrode surfacewhen voltage is imposed upon a symmetric supercapacitor (or EDLC). Therequired ions for this EDL mechanism pre-exist in the liquid electrolyte(randomly distributed in the electrolyte) when the cell is made or in adischarged state.

When the supercapacitor is re-charged, the ions (both cations andanions) already pre-existing in the liquid electrolyte are formed intoEDLs near their respective local electrodes. There is no exchange ofions between an anode active material and a cathode active material. Theamount of charges that can be stored (capacitance) is dictated solely bythe concentrations of cations and anions that pre-exist in theelectrolyte. These concentrations are typically very low and are limitedby the solubility of a salt in a solvent, resulting in a low energydensity.

Since the formation of EDLs does not involve a chemical reaction or anexchange of ions between the two opposite electrodes, the charge ordischarge process of an EDL supercapacitor can be very fast, typicallyin seconds, resulting in a very high power density (more typically3,000-8,000 W/Kg). Compared with batteries, supercapacitors offer ahigher power density, require no maintenance, offer a much highercycle-life, require a very simple charging circuit, and are generallymuch safer. Physical, rather than chemical, energy storage is the keyreason for their safe operation and extraordinarily high cycle-life.

Another type of supercapacitor is a pseudocapacitor that storeselectrical energy by means of reversible faradaic redox reactions on thesurface of suitable carbon electrodes. Such an electrode typically iscomposed of a carbon material (e.g. activated carbon) and a transitionmetal oxide (or a conjugate polymer), which together form a redox pair.Pseudocapacitance is typically accompanied with an electroncharge-transfer between electrolyte and electrode arising from ade-solvated and adsorbed ion whereby only one electron per charge unitparticipates. This faradaic charge transfer originates from a very fastsequence of reversible redox, intercalation or electrosorptionprocesses. The adsorbed ion has no chemical reaction with the atoms ofthe electrode (no chemical bonding) since only a charge-transfer occurs.

Despite the positive attributes of supercapacitors, there are severaltechnological barriers to widespread implementation of supercapacitorsfor various industrial applications. For instance, EDLC supercapacitorspossess very low energy densities when compared to batteries (e.g., 5-8Wh/kg for commercial supercapacitors vs. 20-40 Wh/Kg for the lead acidbattery and 50-100 Wh/kg for the NiMH battery). Although apseudocapacitor can exhibit a higher specific capacitance or energydensity relative to the EDLC, the energy density per cell is typicallylower than 20 Wh/kg. The conventional pseudocapacitor also suffers froma poor cycle life. Lithium-ion batteries possess a much higher energydensity, typically in the range of 150-220 Wh/kg, based on the totalcell weight.

Lithium-Ion Batteries (LIB):

Although possessing a much higher energy density, lithium-ion batteriesdeliver a very low power density (typically 100-500 W/Kg), requiringtypically hours for re-charge. Conventional lithium-ion batteries alsopose some safety concern.

The low power density or long re-charge time of a lithium ion battery isdue to the mechanism of shuttling lithium ions between the interior ofan anode and the interior of a cathode. During recharge, lithium atomsmust diffuse out of a cathode active material (e.g. particles ofLiCoO₂), migrate through an electrolyte phase, and enters orintercalates into the bulk of an anode active material particles (e.g.graphite particles). Most of these lithium ions have to come all the wayfrom the cathode side by diffusing out of the bulk of a cathode activeparticle, through the pores of a solid separator (pores being filledwith a liquid electrolyte), and into the bulk of a graphite particle atthe anode.

During discharge, lithium ions diffuse out of the anode active material(e.g. de-intercalate out of graphite particles 10 μm in diameter),migrate through the liquid electrolyte phase, and then diffuse into thebulk of complex cathode crystals (e.g. intercalate into particleslithium cobalt oxide, lithium iron phosphate, or other lithium insertioncompound). Because the liquid electrolyte only reaches the externalsurface (not interior) of a solid particle (e.g. graphite particle),lithium ions swimming in the liquid electrolyte can only migrate (viafast liquid-state diffusion) to the surface of a graphite particle. Topenetrate into the bulk of a solid graphite particle would require aslow solid-state diffusion (commonly referred to as “intercalation”) oflithium ions. The diffusion coefficients of lithium in solid particlesof lithium metal oxide are relatively low; e.g. typically 10⁻¹⁶-10⁻⁸cm²/sec (more typically 10⁻¹⁴-10⁻¹⁰ cm²/sec), although those of lithiumin liquid are approximately 10⁻⁶ cm²/sec.

As such, these intercalation or solid-state diffusion processes requirea long time to accomplish because solid-state diffusion (or diffusioninside a solid) is difficult and slow. This is why, for instance, thecurrent lithium-ion battery for plug-in hybrid vehicles requires 2-7hours of recharge time, as opposed to just seconds for supercapacitors.The above discussion suggests that an energy storage device that iscapable of storing as much energy as in a battery and yet can be fullyrecharged in one or two minutes like a supercapacitor would beconsidered a revolutionary advancement in energy storage technology.

Lithium Ion Capacitors (LIC):

A hybrid energy storage device that is developed for the purpose ofcombining some features of an EDL supercapacitor (or symmetricsupercapacitor) and those of a lithium-ion battery (LIB) is alithium-ion capacitor (LIC). A LIC contains a lithium intercalationcompound (e.g., graphite particles) as an anode and an EDLcapacitor-type cathode (e.g. activated carbon, AC). In a commonly usedLIC, LiPF₆ is used as an electrolyte salt, which is dissolved in asolvent, such as propylene carbonate. When the LIC is in a chargedstate, lithium ions are retained in the interior of the lithiumintercalation compound anode (i.e. micron-scaled graphite particles) andtheir counter-ions (e.g. negatively charged PF₆ ⁻) are disposed nearactivated carbon surfaces.

When the LIC is discharged, lithium ions migrate out from the interiorof graphite particles (a slow solid-state diffusion process) to enterthe electrolyte phase and, concurrently, the counter-ions PF₆ ⁻ are alsoreleased from the EDL zone, moving further away from AC surfaces intothe bulk of the electrolyte. In other words, both the cations (Li⁺ ions)and the anions (PF₆ ⁻) are randomly disposed in the liquid electrolyte,not associated with any electrode. This implies that the amounts of boththe cations and the anions that dictate the specific capacitance of aLIC are essentially limited by the solubility limit of the lithium saltin a solvent (i.e. limited by the amount of LiPF₆ that can be dissolvedin the solvent) and the surface area of activated carbon in the cathode.Therefore, the energy density of LICs (a maximum of 14 Wh/kg) is notmuch higher than that (6 Wh/kg) of an EDLC (symmetric supercapacitor),and remains an order of magnitude lower than that (most typically150-220 Wh/kg) of a LIB.

Furthermore, due to the need to undergo de-intercalation andintercalation at the anode, the power density of a LIC is not high(typically <10 kW/kg, which is comparable to or only slightly higherthan those of an EDLC).

The above review of the prior art indicates that a battery has a higherenergy density, but is incapable of delivering a high power (highcurrents or pulsed power) that an EV, HEV, or micro-EV needs forstart-stop and accelerating. A battery alone is also not capable ofcapturing and storing the braking energy of a vehicle. A supercapacitoror LIC can deliver a higher power, but does not store much energy (thestored energy only lasts for a short duration of operating time) and,hence, cannot be a single power source alone to meet the energy/powerneeds of an EV or HEV. Thus, there is an urgent need for anelectrochemical energy storage device that delivers both a high energydensity and a high power density.

SUMMARY OF THE INVENTION

The present invention provides an internal hybrid electrochemical cellcomprising:

-   (A) a cathode comprising a cathode active material that contains a    conductive carbon material and a porphyrin compound (e.g. porphyrin,    a porphyrin complex, a chemical derivative of porphyrin, a    chemically functionalized porphyrin, etc.) wherein the porphyrin    compound is bonded to or supported by the carbon material and the    porphyrin compound and the carbon material together form a redox    pair for pseudocapacitance and wherein the carbon material is    selected from activated carbon, activated carbon black, expanded    graphite flakes, exfoliated graphite worms, carbon nanotube, carbon    nanofiber, carbon fiber, a combination thereof, or a combination    thereof with graphene (the porphyrin compound and the carbon    material, when intimately contacted together, form a redox pair    capable of providing large amounts of pseudocapacitance);-   (B) a battery-like anode comprising lithium metal, a lithium metal    alloy, or a prelithiated anode active material selected from the    group consisting of (a) lithiated silicon (Si), germanium (Ge), tin    (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum    (Al), titanium (Ti), cobalt (Co), nickel (Ni), manganese (Mn),    cadmium (Cd), and mixtures thereof; (b) lithiated alloys or    intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co,    Ni, Mn, Cd, and their mixtures; (c) lithiated oxides, carbides,    nitrides, sulfides, phosphides, selenides, tellurides, or    antimonides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn,    Cd, and mixtures or composites thereof (e.g. including lithiated    SiO, lithiated ZnMn₂O₄, etc.); (d) lithiated graphite and carbon    materials; and (e) combinations thereof; and-   (C) a lithium-containing electrolyte in physical contact with the    anode and the cathode; wherein the cathode active material has a    specific surface area no less than 100 m²/g (preferably >500 m²/g,    more preferably >700 m²/g, and most preferably >1000 m²/g) which is    in direct physical contact with the electrolyte. There can be a    porous separator disposed between the anode and the cathode.

In certain embodiments, the porphyrin compound is selected from aporphyrin-transition metal compound. The porphyrin complex is preferablyselected from porphyrin-copper, porphyrin-zinc, porphyrin-nickel,porphyrin-cobalt, porphyrin-manganese, porphyrin-iron, porphyrin-tin,porphyrin-cadmium, porphyrin-vanadium, polyporphyrin, a chemicalderivative, a functionalized porphyrin compound, or a combinationthereof.

The porphyrin compounds are a group of heterocyclic macrocycle organiccompounds, composed of four modified pyrrole subunits interconnected attheir a carbon atoms via methine bridges (═CH—). The parent porphyrin isporphin, and substituted porphines are called porphyrins. The porphyrinring structure is aromatic, with a total of 26 electrons in theconjugated system.

The center of the porphyrin can be empty (FIG. 3(A)) or holds a metalion (e.g. denoted as M in FIG. 3(D)). The porphyrin center can be“coordinated” with a wide array of transition metal elements. Forinstance, M can be V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, In, etc. Differentfunctional groups can be attached to one or more sides of the porphyrinmolecule.

The functional chemical group in porphyrin compound may be selected fromOY, NHY, O═C—OY, P═C—NR′Y, O═C—SY, O═C—Y, —CR′1-OY, N′Y or C′Y, and Y isa functional group of a protein, a peptide, an amino acid, an enzyme, anantibody, a nucleotide, an oligonucleotide, an antigen, or an enzymesubstrate, enzyme inhibitor or the transition state analog of an enzymesubstrate or is selected from R′—OH, R′—NR′₂, R′SH, R′CHO, R′CN, R′X,R′N⁺(R′)₃X⁻, R′SiR′₃, R′Si(—OR′—)_(y)R′_(3-y), R′Si(—O—SiR′₂—)OR′,R′—R″, R′—N—CO, (C₂H₄O—)_(w)H, (—C₃H₆O—)_(w)H, (—C₂H₄O)_(w)—R′,(C₃H₆O)_(w)—R′, R′, and w is an integer greater than one and less than200.

In certain embodiments, porphyrin compound contains a functionalizedporphyrin compound having at least a functional group attached to aporphyrin molecule, wherein the functional group is selected from thegroup consisting of amidoamines, polyamides, aliphatic amines, modifiedaliphatic amines, cycloaliphatic amines, aromatic amines, anhydrides,ketimines, diethylenetriamine (DETA), triethylene-tetramine (TETA),tetraethylene-pentamine (TEPA), polyethylene polyamine, polyamine epoxyadduct, phenolic hardener, non-brominated curing agent, non-aminecuratives, and combinations thereof.

The porphyrin compound may contain a functionalized porphyrin compoundhaving at least a functional group attached to a porphyrin molecule,wherein the functional group contains an azide or bi-radical compoundselected from the group consisting of 2-Azidoethanol,3-Azidopropan-1-amine, 4-(2-Azidoethoxy)-4-oxobutanoic acid,2-Azidoethyl-2-bromo-2-methylpropanoate, chlorocarbonate,azidocarbonate, dichlorocarbene, carbene, aryne, nitrene,(R-)-oxycarbonyl nitrenes, where R=any one of the following groups,

and combinations thereof.

The porphyrin compound is typically a planar molecule and the contactinterface between a porphyrin compound and a graphene sheet or a porousconductive carbon is huge. Such a face-to-face or primarysurface-to-primary surface contact enables fast and massive electroncharge transfer between the two members (carbon and porphyrin compound)of a redox pair, leading to unexpectedly high pseudocapacitance.

In certain preferred embodiments, the conductive carbon material forms amesoporous structure having meso-scaled pores of 2-50 nm and a specificsurface area from 100 m²/g to 3,200 m²/g.

Preferably, the activated carbon in the cathode structure is selectedfrom chemically etched or expanded soft carbon, chemically etched orexpanded hard carbon, exfoliated activated carbon, chemically etchedmulti-walled carbon nanotube, nitrogen-doped carbon nanotube,boron-doped carbon nanotube, chemically doped carbon nanotube,ion-implanted carbon nanotube, chemically treated multi-walled carbonnanotube with an inter-planar separation no less than 0.4 nm, chemicallyexpanded carbon nanofiber, activated carbon fiber, activated graphitefiber, activated carbonized polymer fiber, activated coke, activatedpitch, activated asphalt, activated mesophase carbon, activatedmesoporous carbon, activated electrospun conductive nanofiber, or acombination thereof.

In certain embodiments, the cathode further comprise graphene sheetsincluding single-layer or few-layer graphene, containing up to 10graphene planes. By definition, a few-layer graphene sheet contains 2-10planes of hexagonal carbon atoms (“graphene planes”) stacked togethervia van der Waals forces. Graphene sheets may be selected from pristinegraphene, graphene oxide, reduced graphene oxide, halogenated graphene,hydrogenated graphene, nitrogenated graphene, doped graphene, chemicallyfunctionalized graphene, or a combination thereof.

Although lithium metal (e.g. lithium foil, lithium particles, etc.) orlithium metal alloy (containing >80% by weight of Li element in thealloy) may be used as the anode active material, prelithiated particlesof an anode active material commonly used in a lithium-ion battery (notlithium metal battery) is preferred. The lithium atoms reside in theinterior of the prelithiated particles of the anode active materialbefore the anode (along with a cathode, separator and electrolyte) isassembled into the electrochemical cell. Bare lithium metal is highlyreactive with oxygen and moisture in the air, which may not be conduciveto cell fabrication. More significantly, lithium metal in anelectrochemical cell tends to develop metal surface powdering, deadlithium particles (being separated from Li foil), and dendrite (hence,internal shorting). Surprisingly, the instant approach of prelithiatinganode active material particles can effectively eliminate these issues.

These prelithiated anode active materials may be preferably selectedfrom the group consisting of (a) lithiated silicon (Si), germanium (Ge),tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum(Al), titanium (Ti), cobalt (Co), nickel (Ni), manganese (Mn), cadmium(Cd), and mixtures thereof; (b) lithiated alloys or intermetalliccompounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, andtheir mixtures; (c) lithiated oxides, carbides, nitrides, sulfides,phosphides, selenides, tellurides, or antimonides of Si, Ge, Sn, Pb, Sb,Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or composites thereof;(d) lithiated graphite and carbon materials and (e) combinationsthereof. These materials have been pre-loaded with lithium, pre-reactedwith lithium, and/or pre-intercalated with lithium wherein substantiallyall lithium atoms have reside in the interior or internal structure ofthese materials.

In some preferred embodiments, the battery-like anode comprises aprelithiated anode active material selected from lithiated Si, lithiatedGe, lithiated Sn, lithiated SiO, lithiated SnO₂, lithiated Co₃O₄,lithiated Mn₃O₄, lithiated Fe₃O₄, lithiated ZnMn₂O₄, or a combinationthereof and the anode does not contain lithium metal.

The prelithiated graphite or prelithiated carbon materials in the anodemay be selected from lithiated particles of natural graphite, artificialgraphite, soft carbon, hard carbon, coke (e.g. needle coke), carbonfibers, graphite fibers, carbon nanofibers, carbon nanotubes, carbonnanohorns, expanded graphite platelets, graphene sheets, etc. that havebeen pre-loaded with lithium, pre-reacted with lithium, and/orpre-intercalated with lithium.

Soft carbon and hard carbon are two special groups of carbon materialswell-known in the art. They are not a matter of being “soft” or “hard.”Instead, soft carbon refers to a carbon material having graphiticdomains properly aligned to enable graphitization at a temperaturehigher than 2,500° C. Hard carbon refers to a carbon material havinggraphitic domains that are not conducive to graphitization at atemperature higher than 2,500° C.

In certain embodiments, the anode active material of the internal hybridelectrochemical cell contains prelithiated particles of Si, Ge, SiO, Sn,SnO₂, or a combination thereof.

In some embodiments, the cathode further contains a conductive additiveand the cathode forms a mesoporous structure having a pore size in therange from 2 nm to 50 nm and a specific surface area from 100 m²/g to3,200 m²/g.

The cathode may further contain a resin binder that bonds graphenesheets together. In some embodiments, the cathode further contains aconductive filler selected from graphite or carbon particles, carbonblack, expanded graphite, graphene, carbon nanotube, carbon nanofiber,carbon fiber, conductive polymer, or a combination thereof.

In certain embodiments, the internal hybrid electrochemical cellcontains an anode current collector to support the anode material and/ora cathode current collector to support the cathode material. Preferably,at least one of the anode and the cathode contains a current collectorthat is a porous, electrically conductive material selected from metalfoam, metal web or screen, perforated metal sheet, metal fiber mat,metal nanowire mat, porous conductive polymer film, conductive polymernanofiber mat or paper, conductive polymer foam, carbon foam, carbonaerogel, carbon xerogel, graphene foam, graphene oxide foam, reducedgraphene oxide foam, carbon fiber paper, graphene paper, graphene oxidepaper, reduced graphene oxide paper, carbon nanofiber paper, carbonnanotube paper, or a combination thereof.

In certain preferred embodiments, the anode active material containsprelithiated particles of Si, Ge, SiO, Sn, SnO₂, or a combinationthereof and the prelithiated particles reside in pores of a porous,electrically conductive material selected from metal foam, metal web orscreen, perforated metal sheet, metal fiber mat, metal nanowire mat,porous conductive polymer film, conductive polymer nanofiber mat orpaper, conductive polymer foam, carbon foam, carbon aerogel, carbonxerogel, graphene foam, graphene oxide foam, reduced graphene oxidefoam, carbon fiber paper, graphene paper, graphene oxide paper, reducedgraphene oxide paper, carbon nanofiber paper, carbon nanotube paper, ora combination thereof.

The electrolyte in the internal hybrid electrochemical cell may be anorganic liquid electrolyte, ionic liquid electrolyte, or gel electrolytecontaining an amount of lithium ions when the cell is made.

The invention also provides an energy storage device comprising at leasttwo presently invented internal hybrid electrochemical cells that areconnected in series or in parallel.

The invention also provides an energy device comprising at least oneinternal hybrid electrochemical cell herein invented, which iselectrically connected to an electrochemical cell (e.g. a battery, asupercapacitor, a fuel cell, etc.) in series or in parallel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Schematic of an internal hybrid electrochemical energy storagecell composed of a battery-like anode and a pseudocapacitor cathode,according to an embodiment of the present invention.

FIG. 2 Schematic of a process for producing graphene sheets.

FIG. 3(A) Basic chemical formula of porphyrin.

FIG. 3(B) shows the empty meso positions of a porphyrin molecule.

FIG. 3(C) shows the meso positions being attached with certain chemicalor functional groups.

FIG. 3(D) The center of the porphyrin can hold a metal ion (e.g. denotedas M).

FIG. 3(E) shows the empty β (beta) positions of a porphyrin molecule.

FIG. 3(F) shows some β positions being attached with some chemicalgroups.

FIG. 3(G) The center of the porphyrin holds a metal (Cu) and, inaddition, some side positions are also attached with chemical groups.

FIG. 3(H) The center of the porphyrin holds a metal (Ni) and some sidepositions are also attached with chemical groups.

FIG. 3(I) The center of the porphyrin holds a metal (Fe) and some sidepositions are also attached with chemical groups.

FIG. 3(J) Another example of a chemically functionalized Lewis structurefor meso-tetraphenyl porphyrin—a Lewis structure for meso-tetraphenylporphyrin.

FIG. 3(K) An example of a chemical synthesis route for porphyrin.

FIG. 4 Some representative charge-discharge curve of an internal hybridcell, featuring a lithiated Si anode and a pseudocapacitance cathodecontaining porphyrin copper-bonded porous activated soft carbonparticles.

FIG. 5 The charge storage capacity values (based on the cathode activematerial weight) of two series of internal hybrid cells each featuring alithiated Si anode and a pseudocapacitance cathode containing porphyrincopper-bonded porous activated soft carbon particles or exfoliatedgraphite worms, and those of the cells containing, in the cathode,porphyrin copper only or porous activated soft carbon particles only (orexfoliated graphite worms only) as the cathode active material.

FIG. 6 The charge-discharge cycling curve of an internal hybrid cell,featuring a lithiated Si anode and s pseudocapacitance cathodecontaining porphyrin copper-bonded porous activated soft carbonparticles.

FIG. 7 Ragone plot of three types of electrochemical cells each havingprelithiated SiO as the anode active material: a cell using activatedneedle coke as a cathode active material, a cell using a porphyrin-Ni asthe cathode active material, and porphyrin-Ni-bonded activated needlecoke as a cathode active material.

FIG. 8 Ragone plots of three types of electrochemical cells, each havingprelithiated SnO₂ as the anode active material: (i) a cell usingactivated CNT as a cathode active material, (ii) a cell using afunctionalized porphyrin-Fe as the cathode active material, and (iii) aninternal hybrid cell using functionalized porphyrin-Fe-bonded activatedCNT as a cathode active material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention may be more readily understood by reference to thefollowing detailed description of the invention taken in connection withthe accompanying drawing figures, which form a part of this disclosure.It is to be understood that this invention is not limited to thespecific devices, methods, conditions or parameters described and/orshown herein, and that the terminology used herein is for the purpose ofdescribing particular embodiments by way of example only and is notintended to be limiting the claimed invention.

This invention provides an internal hybrid electrochemical energystorage device that exhibits a power density significantly higher thanthe power densities of conventional supercapacitors and dramaticallyhigher than those of conventional lithium ion batteries. This deviceexhibits an energy density comparable to or higher than those ofbatteries, and significantly higher than those of conventionalsupercapacitors.

In some embodiments of the invention, the internal hybridelectrochemical cell comprises: (A) a cathode comprising a cathodeactive material that contains a conductive carbon material and aporphyrin compound (e.g. porphyrin, a porphyrin complex, a chemicalderivative of porphyrin, a chemically functionalized porphyrin, etc.)wherein the porphyrin compound is bonded to or supported by the carbonmaterial and the porphyrin compound and the carbon material togetherform a redox pair for pseudocapacitance and wherein the carbon materialis selected from activated carbon, activated carbon black, expandedgraphite flakes, exfoliated graphite worms, carbon nanotube, carbonnanofiber, carbon fiber, a combination thereof, or a combination thereofwith graphene (the porphyrin compound and the carbon material, whenintimately contacted together, form a redox pair capable of providinglarge amounts of pseudocapacitance); (B) a battery-like anode comprisinga prelithiated anode active material (e.g. prelithiated Si, SiO, Sn,SnO₂, etc.) and containing no lithium metal, and (C) alithium-containing electrolyte in physical contact with the anode andthe cathode; wherein the cathode active material has a specific surfacearea no less than 100 m²/g which is in direct physical contact with theelectrolyte. The cell is typically and preferably sealed in a protectivecasing (e.g. inside a pouch or steel cylindrical tube) to preventexposure to air.

As illustrated in FIG. 1 as an example, the internal hybridelectrochemical cell has an anode active material layer 10 bonded to ananode current collector 12 using a binder resin (not shown). The anodeactive material layer 10 is composed of multiple prelithiated particles16 of an anode active material (e.g. prelithiated Si particles eachcomposed of Si that was pre-doped or pre-intercalated with Li atomsprior to cell assembly), optional conductive additive (not shown), and aresin binder (e.g. PVDF, SBR; not shown). There can be two anode activematerial layers bonded to the two primary surfaces of an anode currentcollector (e.g. a Cu foil).

The cell also has a cathode active material layer 22 bonded to a cathodecurrent collector 14 using another binder resin (not shown). The cathodeactive material layer 22 is composed of multiple two-component nanosheets (e.g. 20) each containing substantially planar molecules of aporphyrin compound 20 a bonded to a primary surface of a graphene sheet20 b. There can be two cathode active material layers bonded to twoprimary surfaces of a cathode current collector (e.g. Al foil). A porousseparator 18 is disposed between the anode active material layer 10 andthe cathode active material layer 22. Both the anode active materiallayer 10 and cathode active material layer 22 are impregnated with anelectrolyte. The cell is then sealed in a protective housing.

As illustrated in FIG. 3(A)-FIG. 3(K), porphyrin compounds are a groupof heterocyclic macrocycle organic compounds, composed of four modifiedpyrrole subunits interconnected at their a carbon atoms via methinebridges (═CH—). The parent porphyrin is porphin, and substitutedporphines are called porphyrins. The porphyrin ring structure isaromatic, with a total of 26 electrons in the conjugated system.

The center of the porphyrin molecule can be empty (FIG. 3(A)) or hold ametal ion (e.g. denoted as M in FIG. 3(D)). This is commonly referred toas coordination. The porphyrin center can be “coordinated” with a widearray of transition metal elements. For instance, M can be V, Cr, Mn,Fe, Co, Ni, Cu, Zn, Sn, In, etc. Different functional groups can beattached to one or more sides of the porphyrin molecule. As an example,FIG. 3(B) shows the empty meso positions and FIG. 3(C) shows the mesopositions being attached with certain chemical or functional groups.FIG. 3(E) shows the empty β (beta) positions and FIG. 3(F) shows some βpositions being attached with some chemical groups. The center of theporphyrin can hold a metal and, in addition, some side positions arealso attached with chemical groups. Examples are given in FIG. 3(G),FIG. 3(H), and FIG. 3(I). There can be many different combinations ofmany possible functional groups mixed and matched at these side andcenter locations to form different porphyrin complex compounds. Thus,the group of porphyrin and porphyrin complex compounds provides us witha broad array of potential electrode materials.

Preparation of porphyrin compounds can be accomplished in two broadcategories of methods: biosynthesis and chemical synthesis. These arerelatively well-known. For instance, biosynthesis can be used to produceHEME B (FIG. 3(I)).

One of the most common chemical synthesis methods for porphyrins isbased on the work by Paul Rothemund [P. Rothemund, “Formation ofPorphyrins from Pyrrole and Aldehydes,” J. Am. Chem. Soc. (1935) 57(10): 2010-2011; P. Rothemund, “A New Porphyrin Synthesis,” J. Am. Chem.Soc. (1936) 58 (4): 625-627]. These basic techniques have been commonlypracticed in modern chemistry field [e.g. A. D. Adler, et al. “Asimplified synthesis for meso-tetraphenylporphine,” J. Org. Chem. (1967)32 (2): 476-476; Falvo, RaeAnne E.; Mink, Larry M.; Marsh, Diane F.“Microscale Synthesis and ¹H NMR Analysis of Tetraphenylporphyrins,” J.Chem. Educ. 1999 (76): 237-239].

The Rothemund approach is based on a condensation and oxidation,starting with pyrrole and an aldehyde (FIG. 3(K)). In solution-phasesynthesis, acidic conditions are essential; formic acid, acetic acid,and propionic acid are typical reaction solvents. Alternatively,p-toluenesulfonic acid or various Lewis acids can be used with anon-acidic solvent. A large amount of side-product is formed and isremoved, usually by recrystallization or chromatography. Moreenvironmentally green variants of the approach have been developed inwhich the reaction is performed with microwave irradiation usingreactants adsorbed on acidic silica gel or at high temperature in thegas phase. In these cases, no additional acid is required [e.g. Petit,A.; Loupy, A.; Maiuard, P.; Momenteau, M., “Microwave Irradiation in DryMedia: A New and Easy Method for Synthesis of Tetrapyrrolic Compounds,”Synth. Commun. 1992, 22 (8): 1137-114]).

The functional chemical group (e.g. R₁, R₂, R₃, R₄, R₅, or R₆ in FIG.3(G) and FIG. 3(H)) in a porphyrin compound may be selected from OY,NHY, O═C—OY, P═C—NR′Y, O═C—SY, O═C—Y, —CR′1-OY, N′Y or C′Y, and Y is afunctional group of a protein, a peptide, an amino acid, an enzyme, anantibody, a nucleotide, an oligonucleotide, an antigen, or an enzymesubstrate, enzyme inhibitor or the transition state analog of an enzymesubstrate or is selected from, a phenol group, R′—OH, R′—NR′₂, R′SH,R′CHO, R′CN, R′X, R′N⁺(R′)₃X⁻, R′SiR′₃, R′Si(—OR′—)_(y)R′_(3-y),R′Si(—O—SiR′₂—)OR′, R′—R″, R′—N—CO, (C₂H₄O—)_(w)H, (—C₃H₆O—)_(w)H,(—C₂H₄O)_(w)—R′, (C₃H₆O)_(w)—R′, R′, and w is an integer greater thanone and less than 200.

In certain embodiments, porphyrin compound contains a functionalizedporphyrin compound having at least a functional group attached to aporphyrin molecule, wherein the functional group is selected from thegroup consisting of amidoamines, polyamides, aliphatic amines, modifiedaliphatic amines, cycloaliphatic amines, aromatic amines, anhydrides,ketimines, diethylenetriamine (DETA), triethylene-tetramine (TETA),tetraethylene-pentamine (TEPA), polyethylene polyamine, polyamine epoxyadduct, phenolic hardener, non-brominated curing agent, non-aminecuratives, and combinations thereof.

The porphyrin compound may contain a functionalized porphyrin compoundhaving at least a functional group attached to a porphyrin molecule,wherein the functional group contains an azide or bi-radical compoundselected from the group consisting of 2-Azidoethanol,3-Azidopropan-1-amine, 4-(2-Azidoethoxy)-4-oxobutanoic acid,2-Azidoethyl-2-bromo-2-methylpropanoate, chlorocarbonate,azidocarbonate, dichlorocarbene, carbene, aryne, nitrene,(R-)-oxycarbonyl nitrenes, where R=any one of the following groups,

-   -   and combinations thereof.

In the invented cell, the cathode may comprise a cathode active materialthat contains a conductive carbon material and a porphyrin compound(e.g. porphyrin, a porphyrin complex, a chemical derivative ofporphyrin, a chemically functionalized porphyrin, etc.) wherein theporphyrin compound is bonded to or supported by the carbon material andthe porphyrin compound and the carbon material together form a redoxpair for pseudocapacitance.

Preferably, the carbon material is selected from activated carbon,activated carbon black, expanded graphite flakes, exfoliated graphiteworms, carbon nanotube, carbon nanofiber, carbon fiber, a combinationthereof, or a combination thereof with graphene. The porphyrin compoundand the carbon material, when intimately contacted together, form aredox pair capable of providing large amounts of pseudocapacitance.Preferably, the conductive carbon material forms a mesoporous structurehaving meso-scaled pores of 2-50 nm and a specific surface area fromgreater than 100 m²/g to 3,200 m²/g (more preferably >500 m²/g, furthermore preferably >1,000 m²/g, and most preferably >1,500 m²/g).

Preferably, the activated carbon in the cathode structure is selectedfrom chemically etched or expanded soft carbon, chemically etched orexpanded hard carbon, exfoliated activated carbon, chemically etchedmulti-walled carbon nanotube, nitrogen-doped carbon nanotube,boron-doped carbon nanotube, chemically doped carbon nanotube,ion-implanted carbon nanotube, chemically treated multi-walled carbonnanotube (CNT) having an inter-planar separation no less than 0.4 nm,chemically expanded carbon nanofiber (CNF) having an inter-planarseparation no less than 0.4 nm, activated carbon fiber, activatedgraphite fiber, activated carbonized polymer fiber, activated coke,activated pitch, activated asphalt, activated mesophase carbon,activated mesoporous carbon, activated electrospun conductive nanofiber,or a combination thereof. The expanded spacing in the chemicallytreated/expanded CNTs or CNFs is preferably >0.5 nm, morepreferably >0.6 nm, and most preferably >0.8 nm.

These porous and electrically conductive materials are capable ofaccommodating a porphyrin compound in their pores (bonded to pore wallsurfaces as a coating) and, in many cases, capable of protecting theporphyrin compound coating from getting dissolved in a liquidelectrolyte, in addition to providing a 3-D network ofelectron-conducting paths. Quite significantly, the porphyrin compoundand the carbon material (at the pore wall surfaces near a liquidelectrolyte) form a redox pair that give rise to large amounts ofpseudocapacitance.

Conductive carbon nanofiber mats having mesoporous pores can be readilyproduced by electro-spinning of a polymer, which can be carbonized toobtain carbon nanofibers. Also useful are carbon foam, carbon aerogel,and carbon xerogel. These foams may be reinforced with a binder resin,conductive polymer, or CNTs to make a porous structure of goodstructural integrity.

In one preferred embodiment, highly porous graphitic or carbonaceousmaterials may be used to make a conductive and protective backboneporous structure prior to impregnating the resulting porous structurewith a porphyrin compound. In this approach, particles of thesematerials may be bonded by a binder to form a porous structure of goodstructural integrity.

The carbonaceous or graphitic material may be selected from chemicallytreated graphite with an inter-graphene planar separation no less than0.4 nm (preferably greater than 0.5 nm, more preferably greater than 0.6nm) which is not exfoliated, soft carbon (preferably, chemically etchedor expanded soft carbon), hard carbon (preferably, chemically etched orexpanded hard carbon), activated carbon (preferably, exfoliatedactivated carbon), carbon black (preferably, chemically etched orexpanded carbon black), chemically expanded multi-walled carbonnanotube, chemically expanded carbon fiber or nanofiber, or acombination thereof. These carbonaceous or graphitic materials have onething in common; they all have meso-scaled pores, enabling entry ofelectrolyte to access their interior planes.

In one preferred embodiment, the mesoporous carbonaceous material may beproduced by using the following recommended procedures:

-   -   (A) dispersing or immersing a graphitic or carbonaceous material        (e.g., powder of mesophase carbon, meso-carbon micro bead        (MCMB), soft carbon, hard carbon, coke, polymeric carbon        (carbonized resin), activated carbon (AC), carbon black (CB),        multi-walled carbon nanotube (MWCNT), carbon nanofiber (CNF),        carbon or graphite fiber, mesophase pitch fiber, and the like)        in a mixture of an intercalant and/or an oxidant (e.g.,        concentrated sulfuric acid and nitric acid) and/or a        fluorinating agent to obtain a carbon intercalation compound        (CIC), graphite fluoride (GF), or chemically etched/treated        carbon material; and optionally    -   (B) exposing the resulting CIC, GF, or chemically etched/treated        carbon material to a thermal treatment, preferably in a        temperature range of 150-600° C. for a short period of time        (typically 15 to 60 seconds) to obtain expanded carbon.        Alternatively, after step (A) above, the resulting CIC, GF, or        chemically etched/treated carbon material is subjected to        repeated rinsing/washing to remove excess chemical. The rinsed        products are then subjected to a drying procedure to remove        water. The dried CIC, GF, chemically treated CB, chemically        treated AC, chemically treated MWCNT, chemically treated CNF,        chemically treated carbon/graphite/pitch fiber can be used as a        cathode active material (to pair up with a porphyrin compound)        of the presently invented high-capacity cell. These chemically        treated carbonaceous or graphitic materials can be further        subjected to a heat treatment at a temperature preferably in the        range of 150-600° C. for the purposes of creating meso-scaled        pores (2-50 nm) to enable the interior structure being accessed        by electrolyte. It may be noted that these interior graphene        planes remain stacked and interconnected with one another, but        the above-described chemical/thermal treatments facilitate        direct access of these interior graphene planes by the        electrolyte.

The broad array of carbonaceous materials, such as a soft carbon, hardcarbon, polymeric carbon (or carbonized resin), mesophase carbon, coke,carbonized pitch, carbon black, activated carbon, or partiallygraphitized carbon, are commonly referred to as the disordered carbonmaterial. A disordered carbon material is typically formed of two phaseswherein a first phase is small graphite crystal(s) or small stack(s) ofgraphite planes (with typically up to 10 graphite planes or aromaticring structures overlapped together to form a small ordered domain) anda second phase is non-crystalline carbon, and wherein the first phase isdispersed in the second phase or bonded by the second phase. The secondphase is made up of mostly smaller molecules, smaller aromatic rings,defects, and amorphous carbon. Typically, the disordered carbon ishighly porous (e.g., exfoliated activated carbon), or present in anultra-fine powder form (e.g. chemically etched carbon black) havingnano-scaled features (e.g. having meso-scaled pores and, hence, a highspecific surface area).

Soft carbon refers to a carbonaceous material composed of small graphitecrystals wherein the orientations of these graphite crystals or stacksof graphene planes inside the material are conducive to further mergingof neighboring graphene sheets or further growth of these graphitecrystals or graphene stacks using a high-temperature heat treatment.This high temperature treatment is commonly referred to asgraphitization and, hence, soft carbon is said to be graphitizable.

In contrast, hard carbon refers to a carbonaceous material composed ofsmall graphite crystals wherein these graphite crystals or stacks ofgraphene planes inside the material are not oriented in a favorabledirections (e.g. nearly perpendicular to each other) and, hence, are notconducive to further merging of neighboring graphene planes or furthergrowth of these graphite crystals or graphene stacks (i.e., notgraphitizable).

Carbon black (CB) (including acetylene black, AB) and activated carbon(AC) are typically composed of domains of aromatic rings or smallgraphene sheets, wherein aromatic rings or graphene sheets in adjoiningdomains are somehow connected through some chemical bonds in thedisordered phase (matrix). These carbon materials are commonly obtainedfrom thermal decomposition (heat treatment, pyrolyzation, or burning) ofhydrocarbon gases or liquids, or natural products (wood, coconut shells,etc.). These materials per se (without chemical/thermal treatments asdescribed above) are not good candidate cathode materials for thepresently invented high-capacity Li-ion cells. Hence, preferably, theyare subjected to further chemical etching or chemical/thermalexfoliation to form a mesoporous structure having a pore size in therange of 2-50 nm (preferably 2-10 nm). These meso-scaled pores enablethe liquid electrolyte to enter the pores and access the graphene planesinside individual particles of these carbonaceous materials.

The preparation of polymeric carbons by simple pyrolysis of polymers orpetroleum/coal tar pitch materials has been known for approximatelythree decades. When polymers such as polyacrylonitrile (PAN), rayon,cellulose and phenol formaldehyde were heated above 300° C. in an inertatmosphere they gradually lost most of their non-carbon contents. Theresulting structure is generally referred to as a polymeric carbon.Depending upon the heat treatment temperature (HTT) and time, polymericcarbons can be made to be insulating, semi-conducting, or conductingwith the electric conductivity range covering approximately 12 orders ofmagnitude. This wide scope of conductivity values can be furtherextended by doping the polymeric carbon with electron donors oracceptors. These characteristics uniquely qualify polymeric carbons as anovel, easy-to-process class of electro-active materials whosestructures and physical properties can be readily tailor-made.

Polymeric carbons can assume an essentially amorphous structure, or havemultiple graphite crystals or stacks of graphene planes dispersed in anamorphous carbon matrix. Depending upon the HTT used, variousproportions and sizes of graphite crystals and defects are dispersed inan amorphous matrix. Various amounts of two-dimensional condensedaromatic rings or hexagons (precursors to graphene planes) can be foundinside the microstructure of a heat treated polymer such as a PAN fiber.An appreciable amount of small-sized graphene sheets are believed toexist in PAN-based polymeric carbons treated at 300-1,000° C. Thesespecies condense into wider aromatic ring structures (larger-sizedgraphene sheets) and thicker plates (more graphene sheets stackedtogether) with a higher HTT or longer heat treatment time (e.g., >1,500°C.). These graphene platelets or stacks of graphene sheets (basalplanes) are dispersed in a non-crystalline carbon matrix. Such atwo-phase structure is a characteristic of some disordered carbonmaterial.

There are several classes of precursor materials to the disorderedcarbon materials of the instant patent application. For instance, thefirst class includes semi-crystalline PAN in a fiber form. As comparedto phenolic resin, the pyrolized PAN fiber has a higher tendency todevelop small crystallites that are dispersed in a disordered matrix.The second class, represented by phenol formaldehyde, is a moreisotropic, essentially amorphous and highly cross-linked polymer. Thethird class includes petroleum and coal tar pitch materials in bulk orfiber forms. The precursor material composition, heat treatmenttemperature (HTT), and heat treatment time (Htt) are three parametersthat govern the length, width, thickness (number of graphene planes in agraphite crystal), and chemical composition of the resulting disorderedcarbon materials.

In the present investigation, PAN fibers were subjected to oxidation at200-350° C. while under a tension, and then partial or completecarbonization at 350-1,500° C. to obtain polymeric carbons with variousnano-crystalline graphite structures (graphite crystallites). Selectedsamples of these polymeric carbons were further heat-treated at atemperature in the range of 1,500-2,000° C. to partially graphitize thematerials, but still retaining a desired amount of amorphous carbon (noless than 10%). Phenol formaldehyde resin and petroleum and coal tarpitch materials were subjected to similar heat treatments in atemperature range of 500 to 1,500° C. The disordered carbon materialsobtained from PAN fibers or phenolic resins are preferably subjected toa chemical etching/expanding treatment using a process commonly used toproduce activated carbon (e.g., treated in a KOH melt at 900° C. for 1-5hours). This chemical treatment is intended for making the disorderedcarbon mesoporous, enabling electrolyte to reach the edges or surfacesof the constituent aromatic rings after a battery cell is made. Such anarrangement enables the lithium ions in the liquid electrolyte toreadily attach onto exposed graphene planes or edges without having toundergo significant solid-state diffusion.

Certain grades of petroleum pitch or coal tar pitch may be heat-treated(typically at 250-500° C.) to obtain a liquid crystal-type, opticallyanisotropic structure commonly referred to as mesophase. This mesophasematerial can be extracted out of the liquid component of the mixture toproduce isolated mesophase particles or spheres, which can be furthercarbonized and graphitized.

In general, the cathode active material (including the porous backbonestructure and the porphyrin compound bonded to pore wall surfaces) as awhole also preferably form a mesoporous structure with a desired amountof meso-scaled pores (2-50 nm, preferably 2-10 nm) to allow for entry ofelectrolyte. These surface areas of the cathode active material as awhole are typically and preferably >100 m²/g, more preferably >500 m²/g,further more preferably >1,000 m²/g, and most preferably >1,500 m²/g.

A graphene sheet or nano graphene platelet (NGP) is composed of onebasal plane (graphene plane) or multiple basal planes stacked togetherin the thickness direction. In a graphene plane, carbon atoms occupy a2-D hexagonal lattice in which carbon atoms are bonded together throughstrong in-plane covalent bonds. In the c-axis or thickness direction,these graphene planes may be weakly bonded together through van derWaals forces. An NGP can have a platelet thickness from less than 0.34nm (single layer) to 100 nm (multi-layer). For the present electrodeuse, the preferred thickness is <10 nm, more preferably <3 nm (or <10layers), and most preferably single layer graphene. The presentlyinvented graphene-bonded porphyrin material preferably contains mostlysingle-layer graphene, but could make use of some few-layer graphene(less than 10 layers). The graphene sheet may contain a small amount(typically <25% by weight) of non-carbon elements, such as hydrogen,nitrogen, fluorine, and oxygen, which are attached to an edge or surfaceof the graphene plane.

Graphene sheets (herein also referred to as nano graphene platelets,NGPs) may be produced by using several processes, discussed below:

Referring to FIG. 2, graphite oxide may be prepared by dispersing orimmersing a laminar graphite material (e.g., powder of natural flakegraphite or synthetic graphite) in an oxidizing agent, typically amixture of an intercalant (e.g., concentrated sulfuric acid) and anoxidant (e.g., nitric acid, hydrogen peroxide, sodium perchlorate,potassium permanganate) at a desired temperature (typically 0-70° C.)for a sufficient length of time (typically 30 minutes to 5 days) toobtain graphite intercalation compound (GIC) or graphite oxide. If thegraphite intercalation time is from 0.5 to 5 hours, the GIC tends to beincompletely intercalated (predominately non-Stage-1 GIC). The GICparticles may then be exposed to a thermal shock, preferably in atemperature range of 600-1,100° C. for typically 15 to 60 seconds toobtain exfoliated graphite or graphite worms.

The exfoliated graphite worms from thermal exfoliation of incompletelyintercalated GIC may be subjected to mechanical shearing (e.g. using amechanical shearing machine or an ultrasonicator) to break up thegraphite flakes that constitute a graphite worm. The resulting graphiteflakes, typically having a thickness higher than 100 nm, are commonlyreferred to as “expanded graphite” or “expanded graphite flakes.”

If the GICs are mostly Stage-1 species or heavily oxidized graphite,thermal exfoliation of these GICs/graphite oxide can directly result inthe formation of separated graphene sheets (1-10 graphene planes). Theun-broken graphite worms or individual graphite flakes may be dispersedin water, acid, or organic solvent and ultrasonicated to obtain isolatedgraphene sheets.

The pristine graphene material is preferably produced by one of thefollowing three processes: (A) Intercalating the graphitic material witha non-oxidizing agent, followed by a thermal or chemical exfoliationtreatment in a non-oxidizing environment; (B) Subjecting the graphiticmaterial to a supercritical fluid environment for inter-graphene layerpenetration and exfoliation; or (C) Dispersing the graphitic material ina powder form to an aqueous solution containing a surfactant ordispersing agent to obtain a suspension and subjecting the suspension todirect ultrasonication.

In Procedure (A), a particularly preferred step comprises (i)intercalating the graphitic material with a non-oxidizing agent,selected from an alkali metal (e.g., potassium, sodium, lithium, orcesium), alkaline earth metal, or an alloy, mixture, or eutectic of analkali or alkaline metal; and (ii) a chemical exfoliation treatment(e.g., by immersing potassium-intercalated graphite in ethanolsolution).

In Procedure (B), a preferred step comprises immersing the graphiticmaterial to a supercritical fluid, such as carbon dioxide (e.g., attemperature T>31° C. and pressure P>7.4 MPa) and water (e.g., at T>374°C. and P>22.1 MPa), for a period of time sufficient for inter-graphenelayer penetration (tentative intercalation). This step is then followedby a sudden de-pressurization to exfoliate individual graphene layers.Other suitable supercritical fluids include methane, ethane, ethylene,hydrogen peroxide, ozone, water oxidation (water containing a highconcentration of dissolved oxygen), or a mixture thereof.

In Procedure (C), a preferred step comprises (a) dispersing particles ofa graphitic material in a liquid medium containing therein a surfactantor dispersing agent to obtain a suspension or slurry; and (b) exposingthe suspension or slurry to ultrasonic waves (a process commonlyreferred to as ultrasonication) at an energy level for a sufficientlength of time to produce the separated nano-scaled platelets, which arepristine, non-oxidized NGPs.

NGPs can be produced with an oxygen content no greater than 25% byweight, preferably below 20% by weight, further preferably below 5%.Typically, the oxygen content is between 5% and 20% by weight. Theoxygen content can be determined using chemical elemental analysisand/or X-ray photoelectron spectroscopy (XPS).

The laminar graphite materials used in the prior art processes for theproduction of the GIC, graphite oxide, and subsequently made exfoliatedgraphite, flexible graphite sheets, and graphene platelets were, in mostcases, natural graphite. However, the starting material may be selectedfrom the group consisting of natural graphite, artificial graphite(e.g., highly oriented pyrolytic graphite, HOPG), graphite oxide,graphite fluoride, graphite fiber, carbon fiber, carbon nanofiber,carbon nanotube, mesophase carbon micro-bead (MCMB) or carbonaceousmicro-sphere (CMS), soft carbon, hard carbon, and combinations thereof.All of these materials contain graphite crystallites that are composedof layers of graphene planes stacked or bonded together via van derWaals forces. In natural graphite, multiple stacks of graphene planes,with the graphene plane orientation varying from stack to stack, areclustered together. In carbon fibers, the graphene planes are usuallyoriented along a preferred direction. Generally speaking, soft carbonsare carbonaceous materials obtained from carbonization of liquid-state,aromatic molecules. Their aromatic ring or graphene structures are moreor less parallel to one another, enabling further graphitization. Hardcarbons are carbonaceous materials obtained from aromatic solidmaterials (e.g., polymers, such as phenolic resin and polyfurfurylalcohol). Their graphene structures are relatively randomly orientedand, hence, further graphitization is difficult to achieve even at atemperature higher than 2,500° C. But, graphene sheets do exist in thesecarbons.

The presently invented process typically resulted in nano graphenesheets that, when formed into a thin film with a thickness no greaterthan 100 nm, exhibits an electrical conductivity of at least 10 S/cm,often higher than 100 S/cm, and, in many cases, higher than 1,000 S/cm.The resulting NGP powder material typically has a specific surface areafrom approximately 300 m²/g to 2,600 m²/g and, in many cases, comprisessingle-layer graphene or few-layer graphene sheets.

When these graphene sheets are combined with a porphyrin compound toform graphene-porphyrin compound hybrid sheets, these hybrid 2Dstructures (when packed into a dry electrode) exhibit an electricalconductivity typically no less than 10⁻² S/cm (typically and preferablygreater than 1 S/cm and most typically and preferably greater than 100S/cm; some being greater than 2,000 S/cm). The graphene component istypically in an amount of from 0.5% to 99% by weight (preferably from 1%to 90% by weight and more preferably between 5% and 80%) based on thetotal weight of graphene and the porphyrin compound combined.

Graphene sheets may be oxidized to various extents during theirpreparation, resulting in graphite oxide or graphene oxide (GO). Hence,in the present context, graphene preferably or primarily refers to thosegraphene sheets containing no or low oxygen content; but, they caninclude GO of various oxygen contents. Further, graphene may befluorinated to a controlled extent to obtain graphene fluoride.

The NGPs may be obtained from exfoliation and platelet separation of anatural graphite, synthetic graphite, highly oriented pyrolyticgraphite, graphite fiber, carbon fiber, carbon nanofiber, graphiticnanofiber, spherical graphite or graphite globule, mesophase micro-bead,mesophase pitch, graphitic coke, or graphitized polymeric carbon.

For instance, as discussed earlier, the graphene oxide may be obtainedby immersing powders or filaments of a starting graphitic material (e.g.natural graphite powder) in an oxidizing liquid medium (e.g. a mixtureof sulfuric acid, nitric acid, and potassium permanganate) in a reactionvessel at a desired temperature for a period of time (typically from 0.5to 96 hours, depending upon the nature of the starting material and thetype of oxidizing agent used). The resulting graphite oxide particlesmay then be subjected to thermal exfoliation or ultrasonic wave-inducedexfoliation to produce GO sheets.

Pristine graphene may be produced by direct ultrasonication (also knownas liquid phase production) or supercritical fluid exfoliation ofgraphite particles. These processes are well-known in the art. Multiplepristine graphene sheets may be dispersed in water or other liquidmedium with the assistance of a surfactant to form a suspension.

Fluorinated graphene or graphene fluoride is herein used as an exampleof the halogenated graphene material group. There are two differentapproaches that have been followed to produce fluorinated graphene: (1)fluorination of pre-synthesized graphene: This approach entails treatinggraphene prepared by mechanical exfoliation or by CVD growth withfluorinating agent such as XeF₂, or F-based plasmas; (2) Exfoliation ofmultilayered graphite fluorides: Both mechanical exfoliation and liquidphase exfoliation of graphite fluoride can be readily accomplished [F.Karlicky, et al. “Halogenated Graphenes: Rapidly Growing Family ofGraphene Derivatives” ACS Nano, 2013, 7 (8), pp 6434-6464].

Interaction of F₂ with graphite at high temperature leads to covalentgraphite fluorides (CF)_(n) or (C₂F)_(n), while at low temperaturesgraphite intercalation compounds (GIC) C_(x)F (2≤x≤24) form. In (CF)_(n)carbon atoms are sp3-hybridized and thus the fluorocarbon layers arecorrugated consisting of trans-linked cyclohexane chairs. In (C₂F)_(n)only half of the C atoms are fluorinated and every pair of the adjacentcarbon sheets are linked together by covalent C—C bonds. Systematicstudies on the fluorination reaction showed that the resulting F/C ratiois largely dependent on the fluorination temperature, the partialpressure of the fluorine in the fluorinating gas, and physicalcharacteristics of the graphite precursor, including the degree ofgraphitization, particle size, and specific surface area. In addition tofluorine (F₂), other fluorinating agents may be used, although most ofthe available literature involves fluorination with F₂ gas, sometimes inpresence of fluorides.

For exfoliating a layered precursor material to the state of individuallayers or few-layers, it is necessary to overcome the attractive forcesbetween adjacent layers and to further stabilize the layers. This may beachieved by either covalent modification of the graphene surface byfunctional groups or by non-covalent modification using specificsolvents, surfactants, polymers, or donor-acceptor aromatic molecules.The process of liquid phase exfoliation includes ultrasonic treatment ofa graphite fluoride in a liquid medium.

The nitrogenation of graphene can be conducted by exposing a graphenematerial, such as graphene oxide, to ammonia at high temperatures(200-400° C.). Nitrogenated graphene could also be formed at lowertemperatures by a hydrothermal method; e.g. by sealing GO and ammonia inan autoclave and then increased the temperature to 150-250° C. Othermethods to synthesize nitrogen doped graphene include nitrogen plasmatreatment on graphene, arc-discharge between graphite electrodes in thepresence of ammonia, ammonolysis of graphene oxide under CVD conditions,and hydrothermal treatment of graphene oxide and urea at differenttemperatures.

It has been commonly believed that a high specific surface area is anundesirable feature of cathodes (particularly transition metal oxidecathodes) for lithium-ion cells based on the belief that a high surfacearea leads to the formation of more solid-electrolyte interface (SEI), acommon cause of capacity irreversibility or capacity loss. We haveherein defied this expectation and discovered that these porphyrincompounds, coupled with graphene, can be superior cathode materials forthe instant internal hybrid cells, which could operate tens of thousandsof cycles without any significant capacity decay. Also surprisingly,these porphyrin compounds, when bonded to graphene sheet surfaces in aface-to-face manner and when the specific surface area of the resultingcathode exceeds 100 m²/g (preferably >500 m²/g), exhibit a specificcapacity significantly higher than those of conventional pseudocapacitorelectrode.

A conductive additive is generally not needed since graphene sheets areconducting even though the porphyrin compound are generally notelectrically conducting. However, one may choose to add a conductiveadditive and/or a binder material (e.g. binder resin or carbonizedresin) to form an electrode of structural integrity. The conductiveadditive or filler may be selected from any electrically conductivematerial, but is advantageously selected from graphite or carbonparticles, carbon black, expanded graphite, graphene, carbon nanotube,carbon nanofiber, carbon fiber, conductive polymer, or a combinationthereof. The amount of conductive fillers is preferably no greater than30% by weight based on the total cathode electrode weight (withoutcounting the cathode current collector weight), preferably no greaterthan 15% by weight, and most preferably no greater than 10% by weight.The amount of binder material is preferably no greater than 15% byweight, more preferably no greater than 10%, and most preferably nogreater than 5% by weight. It is important to note that theporphyrin-bonded graphene sheets, with or without the conductive fillerand binder, must form an electrode having a specific surface areagreater than 100 m²/g (preferably >500 m²/g).

The internal hybrid cell contains a negative electrode (including anoptional current collector and an anode active material layer)containing a high-capacity active material (e.g. Si, Ge, Sn, SiO, SnO₂,etc.) that is prelithiated before the anode active material layer ismade. Preferred electrolyte types include organic liquid electrolyte,gel electrolyte, and ionic liquid electrolyte (preferably containinglithium salts dissolved therein), or a combination thereof, although onemay choose to use aqueous or solid electrolytes.

In one preferred embodiment, the anode active material is selected froma lithium intercalation compound, a lithiated compound, lithiatedtitanium dioxide, lithium titanate, lithium manganate, a lithiumtransition metal oxide, Li₄Ti₅O₁₂, or a combination thereof. The lithiumintercalation compound or lithiated compound may be selected from thefollowing groups of materials: (a) Lithiated silicon (Si), germanium(Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn),aluminum (Al), titanium (Ti), cobalt (Co), nickel (Ni), manganese (Mn),cadmium (Cd), and mixtures thereof; (b) Lithiated alloys orintermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni,Mn, Cd, and their mixtures; (c) Lithiated oxides, carbides, nitrides,sulfides, phosphides, selenides, tellurides, or antimonides of Si, Ge,Sn, Pb, Sb, Bi, Zn, Al, Fe, Co, Ni, Mn, Cd, and mixtures or compositesthereof, (d) Lithiated salts or hydroxides of Sn; or (e) lithiatedgraphite and carbon materials. Preferably, there is no lithium metal(e.g. Li foil, Li chips, Li particles, etc.) present in the internalhybrid electrochemical cell.

Prior to prelithiation, particles of the non-carbon based anode activematerial may be coated with a carbonizable coating material (e.g.,phenolic resin, poly(furfuryl alcohol), coal tar pitch, or petroleumpitch). The coating can then be carbonized to produce an amorphouscarbon or polymeric carbon coating on the surface of these Si particles.Such a conductive surface coating can help maintain a network ofelectron-conducting paths during repeated charge/discharge cycles andprevent undesirable chemical reactions between Si and electrolyte fromhappening. Hence, the presently invented method may further comprise astep of coating a surface of the fine particles with a thin layer ofcarbon having a thickness less than 1 μm prior to being subjected tolithiating. The thin layer of carbon preferably has a thickness lessthan 100 nm. Such a thin layer of carbon may be obtained frompyrolization of a polymer, pitch, or organic precursor or obtained bychemical vapor deposition, physical vapor deposition, sputtering, etc.

Alternatively, the particles of an anode active material may be coatedwith a layer of graphene, electron-conducting polymer, or ion-conductingpolymer. Such coating processes are well-known in the art.

Prelithiation can be accomplished in several different ways that can beclassified into 3 categories: physical methods, electrochemical methods,and chemical methods. These methods are well-known in the art. Amongthese, the electrochemical intercalation is the most effective. Lithiumions can be intercalated into non-Li elements (e.g. Si, Ge, and Sn) andcompounds (e.g. SnO₂ and Co₃O₄) up to a weight percentage of 54.68% (seeTable 1 below). For Zn, Mg, Ag, and Au, the amount of Li can reach 99%by weight.

TABLE 1 Lithium storage capacity of selected non-Li elements.Intercalated Atomic weight Atomic weight of Max. wt. % compound of Li,g/mole active material, g/mole of Li Li₄Si 6.941 28.086 49.71 Li_(4.4)Si6.941 28.086 54.68 Li_(4.4)Ge 6.941 72.61 30.43 Li4.4Sn 6.941 118.7120.85 Li₃Cd 6.941 112.411 14.86 Li₃Sb 6.941 121.76 13.93 Li_(4.4)Pb6.941 207.2 13.00 LiZn 6.941 65.39 7.45 Li₃Bi 6.941 208.98 8.80

In the prelithiated particles, the lithium atoms reside in the interiorof the anode active material particles before the anode, a cathode, aseparator and electrolyte are assembled to become an electrochemicalcell. Bare lithium metal is highly reactive with oxygen and moisture inthe air, which is not conducive to cell fabrication. Prelithiation ofanode active material particles eliminates this shortcoming. Moresignificantly, lithium metal in an electrochemical cell tends to developmetal surface powdering, dead lithium particles (being separated from Lifoil), and dendrite (hence, internal shorting). Surprisingly, theinstant strategy of using prelithiated anode active material particleseffectively eliminates these issues.

The particles of the anode active material may be in the form of a nanoparticle, nanowire, nanofiber, nano tube, nano sheet, nano platelet,nano disc, nano belt, nano ribbon, or nano horn. They can benon-lithiated (when incorporated into the anode active material layer)or pre-lithiated to a desired extent (up to the maximum capacity asallowed for a specific element or compound.

In a prior art lithium-ion capacitor (LIC), the primary cathode activematerial is a carbon material (e.g., activated carbon or CNT bundles),and lithium titanate or lithiated graphite particles constitute theanode. In other cases, a sacrificial lithium metal foil is implementedinto the LIC cell. This lithium metal layer is then partially orentirely ionized and dissolved during the first discharge cycle of thecell. The carbon material in a conventional LIC cathode provideselectric double layers of charges. In contrast, the cathode of instantinternal hybrid cell is based on graphene-porphyrin compound redox pairsthat produce pseudocapacitance. Additionally, the anode active materialis a prelithiated high-capacity material, such as prelithiated Si, Ge,Sn, SiO, and SnO₂. Preferably, there is no lithium layer (Li metal foilor Li metal particles, for instance) that is added into the presentlyinvented internal hybrid cell; instead, just prelithiated particles ofan anode active material Such a strategy obviates the need to handlelithium metal during cell manufacturing, which is challenging andexpensive; cell production must be conducted in a battery-grade dryroom.

A wide range of electrolytes can be used for practicing the instantinvention. Most preferred are non-aqueous organic and/or ionic liquidelectrolytes. The non-aqueous electrolyte to be employed herein may beproduced by dissolving an electrolytic salt in a non-aqueous solvent.Any known non-aqueous solvent which has been employed as a solvent for alithium secondary battery can be employed. A non-aqueous solvent mainlyconsisting of a mixed solvent comprising ethylene carbonate (EC) and atleast one kind of non-aqueous solvent whose melting point is lower thanthat of aforementioned ethylene carbonate and whose donor number is 18or less (hereinafter referred to as a second solvent) may be preferablyemployed. This non-aqueous solvent is advantageous in that it is (a)stable against a negative electrode containing a carbonaceous materialwell developed in graphite structure; (b) effective in suppressing thereductive or oxidative decomposition of electrolyte; and (c) high inconductivity. A non-aqueous electrolyte solely composed of ethylenecarbonate (EC) is advantageous in that it is relatively stable againstdecomposition through a reduction by a graphitized carbonaceousmaterial. However, the melting point of EC is relatively high, 39 to 40°C., and the viscosity thereof is relatively high, so that theconductivity thereof is low, thus making EC alone unsuited for use as asecondary battery electrolyte to be operated at room temperature orlower. The second solvent to be used in a mixture with EC functions tomake the viscosity of the solvent mixture lower than that of EC alone,thereby promoting the ion conductivity of the mixed solvent.Furthermore, when the second solvent having a donor number of 18 or less(the donor number of ethylene carbonate is 16.4) is employed, theaforementioned ethylene carbonate can be easily and selectively solvatedwith lithium ion, so that the reduction reaction of the second solventwith the carbonaceous material well developed in graphitization isassumed to be suppressed. Further, when the donor number of the secondsolvent is controlled to not more than 18, the oxidative decompositionpotential to the lithium electrode can be easily increased to 4 V ormore, so that it is possible to manufacture a lithium secondary batteryof high voltage.

Preferable second solvents are dimethyl carbonate (DMC), methylethylcarbonate (MEC), diethyl carbonate (DEC), ethyl propionate, methylpropionate, propylene carbonate (PC), γ-butyrolactone (gamma-BL),acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methylformate (MF), toluene, xylene and methyl acetate (MA). These secondsolvents may be employed singly or in a combination of two or more. Moredesirably, this second solvent should be selected from those having adonor number of 16.5 or less. The viscosity of this second solventshould preferably be 28 cps or less at 25° C.

The mixing ratio of the aforementioned ethylene carbonate in the mixedsolvent should preferably be 10 to 80% by volume. If the mixing ratio ofthe ethylene carbonate falls outside this range, the conductivity of thesolvent may be lowered or the solvent tends to be more easilydecomposed, thereby deteriorating the charge/discharge efficiency. Morepreferable mixing ratio of the ethylene carbonate is 20 to 75% byvolume. When the mixing ratio of ethylene carbonate in a non-aqueoussolvent is increased to 20% by volume or more, the solvating effect ofethylene carbonate to lithium ions will be facilitated and the solventdecomposition-inhibiting effect thereof can be improved.

Examples of preferred mixed solvent are a composition comprising EC andMEC; comprising EC, PC and MEC; comprising EC, MEC and DEC; comprisingEC, MEC and DMC; and comprising EC, MEC, PC and DEC; with the volumeratio of MEC being controlled within the range of 30 to 80%. Byselecting the volume ratio of MEC from the range of 30 to 80%, morepreferably 40 to 70%, the conductivity of the solvent can be improved.The electrolytic salts to be incorporated into a non-aqueous electrolytemay be selected from a lithium salt, such as lithium perchlorate(LiClO₄), lithium hexafluorophosphate (LiPF₆), lithium borofluoride(LiBF₄), lithium hexafluoroarsenide (LiAsF₆), lithiumtrifluoro-metasulfonate (LiCF₃SO₃) and bis-trifluoromethyl sulfonylimidelithium [LiN(CF₃SO₂)₂]. Among them, LiPF₆, LiBF₄ and LiN(CF₃SO₂)₂ arepreferred. The content of aforementioned electrolytic salts in thenon-aqueous solvent is preferably 0.5 to 2.0 mol/l.

The ionic liquid is composed of ions only. Ionic liquids are low meltingtemperature salts that are in a molten or liquid state when above adesired temperature. For instance, a salt is considered as an ionicliquid if its melting point is below 100° C. If the melting temperatureis equal to or lower than room temperature (25° C.), the salt isreferred to as a room temperature ionic liquid (RTIL). The IL salts arecharacterized by weak interactions, due to the combination of a largecation and a charge-delocalized anion. This results in a low tendency tocrystallize due to flexibility (anion) and asymmetry (cation).

A typical and well-known ionic liquid is formed by the combination of a1-ethyl-3-methylimidazolium (EMI) cation and anN,N-bis(trifluoromethane)sulphonamide (TFSI) anion. This combinationgives a fluid with an ionic conductivity comparable to many organicelectrolyte solutions and a low decomposition propensity and low vaporpressure up to ˜300-400° C. This implies a generally low volatility andnon-flammability and, hence, a much safer electrolyte for batteries.

Ionic liquids are basically composed of organic ions that come in anessentially unlimited number of structural variations owing to thepreparation ease of a large variety of their components. Thus, variouskinds of salts can be used to design the ionic liquid that has thedesired properties for a given application. These include, among others,imidazolium, pyrrolidinium and quaternary ammonium salts as cations andbis(trifluoromethanesulphonyl) imide, bis(fluorosulphonyl)imide, andhexafluorophosphate as anions. Based on their compositions, ionicliquids come in different classes that basically include aprotic, proticand zwitterionic types, each one suitable for a specific application.

Common cations of room temperature ionic liquids (RTILs) include, butnot limited to, tetraalkylammonium, di-, tri-, andtetra-alkylimidazolium, alkylpyridinium, dialkyl-pyrrolidinium,dialkylpiperidinium, tetraalkylphosphonium, and trialkylsulfonium.Common anions of RTILs include, but not limited to, BF₄ ⁻, B(CN)₄ ⁻,CH₃BF₃—, CH2CHBF₃ ⁻, CF₃BF₃ ⁻, C₂F₅BF₃ ⁻, n-C₃F₇BF₃ ⁻, n-C₄F₉BF₃ ⁻, PF₆⁻, CF₃CO₂ ⁻, CF₃SO₃ ⁻, N(SO₂CF₃)₂ ⁻, N(COCF₃)(SO₂CF₃)⁻, N(SO₂F)₂ ⁻,N(CN)₂ ⁻, C(CN)₃ ⁻, SCN⁻, SeCN⁻, CuCl₂ ⁻, AlCl₄ ⁻, F(HF)_(2.3) ⁻, etc.Relatively speaking, the combination of imidazolium- or sulfonium-basedcations and complex halide anions such as AlCl₄ ⁻, BF₄ ⁻, CF₃CO₂ ⁻,CF₃SO₃ ⁻, NTf₂ ⁻, N(SO₂F)₂ ⁻, or F(HF)_(2.3) ⁻ results in RTILs withgood working conductivities.

RTILs can possess archetypical properties such as high intrinsic ionicconductivity, high thermal stability, low volatility, low (practicallyzero) vapor pressure, non-flammability, the ability to remain liquid ata wide range of temperatures above and below room temperature, highpolarity, high viscosity, and wide electrochemical windows. Theseproperties, except for the high viscosity, are desirable attributes whenit comes to using an RTIL as an electrolyte ingredient (a salt and/or asolvent) in a supercapacitor.

The following examples serve to illustrate the preferred embodiments ofthe present invention and should not be construed as limiting the scopeof the invention:

Example 1: Mesoporous Soft Carbon as a Redox Partner with a PorphyrinCompound

Chemically etched or expanded soft carbon was prepared fromheat-treating a liquid crystalline aromatic resin (50/50 mixture ofanthracene and pyrene) at 200° C. for 1 hour. The resin was ground witha mortar, and calcined at 900° C. for 2 h in a N₂ atmosphere to preparethe graphitizable carbon or soft carbon. The resulting soft carbon wasmixed with small tablets of KOH (four-fold weight) in an alumina meltingpot. Subsequently, the soft carbon containing KOH was heated at 750° C.for 2 h in N₂. Upon cooling, the alkali-rich residual carbon was washedwith hot water until the outlet water reached a pH value of 7. Theresulting chemically etched or expanded soft carbon was dried by heatingat 60° C. in a vacuum for 24 hours. This material can be used in boththe anode and cathode due to its high specific surface area and itsability to capture and store lithium atoms on its surfaces. Thesesurfaces (inside pores) were also found to be particularly suitable forforming a redox pair with a porphyrin compound.

Example 2: Expanded “Activated Carbon” (E-AC)

Activated carbon (AC, from Ashbury Carbon Co.) was treated with an acidsolution (sulfuric acid, nitric acid, and potassium permanganate at aratio of 4:1:0.05) for 24 hours. Upon completion of the reaction, themixture was poured into deionized water and filtered. The treated AC wasrepeatedly washed in a 5% solution of HCl to remove most of the sulphateions. The sample was then washed repeatedly with deionized water untilthe pH of the filtrate was neutral. The slurry was then dried in avacuum oven pre-set at 70° C. for 24 hours. The dried sample was thenplaced in a tube furnace at 1,050° C. for 2 minutes to obtain expandedAC. This material can be used in both the anode and cathode of a lithiumcell due to its high specific surface area and ability to capture andstore Li atoms on its surfaces. These surfaces on the pore walls werealso found to be particularly suitable for forming a redox pair with aporphyrin compound.

Example 3: Chemically Treated (Expanded) Needle Coke

Anisotropic needle coke has a fully developed needle-shape texture ofoptical anisotropy. Volatile species of the raw coke was estimated to bearound 5 wt. %. Activation was carried out using KOH in a reactionapparatus that consisted of a stainless steel tube and a nickel sampleholder. KOH activation was carried out at 800° C. for 2 h under Ar flow.The coke/KOH ratio was varied between 1/1 and 1/4. Upon cooling, thealkali-rich coke was washed with hot water until the outlet waterreached a pH value of 7. The resulting chemically etched or expandedcoke was dried by heating at 60° C. in a vacuum for 24 hours. Thetreated coke is highly porous, having a pore size range of approximately1-85 nm.

Example 4: Chemically Treated (Expanded) Petroleum Pitch-Derived HardCarbon

A pitch sample (A-500 from Ashland Chemical Co.) was carbonized in atube furnace at 900° C. for 2 hours, followed by further carbonizationat 1,200° C. for 4 hours. KOH activation was carried out at 800° C. for2 h under Ar flow to open up the internal structure of pitch-based hardcarbon particles. The hard carbon-based porous structure was found tohave a pore size range of 3-100 nm (mostly <50 nm) and to beparticularly suitable for forming a redox pair with a porphyrincompound.

Example 5: Chemically Activated Mesophase Carbon and Production ofFluorinated Carbon

Meso-carbon carbon particles (un-graphitized MCMBs) were supplied fromChina Steel Chemical Co. This material has a density of about 2.2 g/cm³with a median particle size of about 16 μm. This batch of mesophasecarbon was divided into two samples. One sample was immersed in K₂CO₃ at900° C. for 1 h to form chemically activated meso-carbon. The chemicallyactivated mesophase carbons showed a BET specific surface area of 1,420m²/g. This material can be used in both the anode and cathode due to itshigh specific surface area and ability to capture and store metal atomson its surfaces. These surfaces were found to be particularly suitablefor forming a redox pair with a porphyrin compound.

The other sample was subjected to a fluorination treatment. Themesophase carbon particles were mixed with a PVDF binder in a NMPsolution and coated onto an Al foil to form an electrode sheet. Thiselectrode sheet was used as a working electrode in an electrochemicalfluorination treatment apparatus consisting of a PTFE beaker, a Pt platecounter electrode, a Pd wire as a reference electrode, and (C₂H₅)₃N-3HFas electrolyte. The fluorination procedure was carried out at roomtemperature by potential sweeping from −1.0 V to 1.0 V at a 20 mV/s scanrate. X-ray diffraction data indicate that the inter-graphene spacinghas been increased from 0.337 nm to 0.723 nm.

Example 6: Graphitic Fibrils from Pitch-Based Carbon Fibers for Forminga Porous Structure

Fifty grams of graphite fibers were intercalated with a mixture ofsulfuric acid, nitric acid, and potassium permanganate at a weight ratioof 4:1:0.05 (graphite-to-intercalate ratio of 1:3) for 24 hours. Uponcompletion of the intercalation reaction, the mixture was poured intodeionized water and filtered. The sample was then washed with 5% HClsolution to remove most of the sulfate ions and residual salt and thenrepeatedly rinsed with deionized water until the pH of the filtrate wasapproximately 5. The dried sample was then exposed to a heat shocktreatment at 950° C. for 45 seconds. The sample was then submitted to amechanical shearing treatment in a Cowles (a rotating-bladedissolver/disperser) for 10 minutes. The resulting graphitic fibrilswere examined using SEM and TEM and their length and diameter weremeasured. Graphitic fibrils, alone or in combination with anotherparticulate carbon/graphite material, can be packed into a mesoporousstructure for supporting porphyrin compounds.

Example 7: Expanded Multi-Walled Carbon Nanotubes (MWCNTs)

Fifty grams of MWCNTs were chemically treated (intercalated and/oroxidized) with a mixture of sulfuric acid, nitric acid, and potassiumpermanganate at a weight ratio of 4:1:0.05 (graphite-to-intercalateratio of 1:3) for 48 hours. Upon completion of the intercalationreaction, the mixture was poured into deionized water and filtered. Thesample was then washed with 5% HCl solution to remove most of thesulfate ions and residual salt and then repeatedly rinsed with deionizedwater until the pH of the filtrate was approximately 5. The dried samplewas then exposed to a heat shock treatment at 950° C. for 45 seconds.Expanded MWCNTs, alone or in combination with another particulatecarbon/graphite material, can be packed into a mesoporous structure forsupporting porphyrin compounds.

Example 8: Preparation of Internal Hybrid Cells Featuring a ConductingCarbon/Porphyrin Cathode

A functionalized porphyrin,[5,15-bis-(ethynyl)-10,20-diphenylporphinato]copper(II) (CuDEPP), wassynthesized according to Gao, et al. [Ping Gao, et al. “A PorphyrinComplex as a Self-Conditioned Electrode Material for High-PerformanceEnergy Storage,” Angewandte Chemie, Vol. 129, Issue 35, Aug. 21, 2017,Pages 10477-10482; Supporting Information]. However, the instantprocedure has a major deviation from Gao's in that porous activated softcarbon particles were added into the THF solution during the final phaseof CuDEPP preparation. Specifically,[5,15-Bis(trimethylsilylethynl)-10,20-dipheny)porphinato]copper(II)(0.322 g, 0.45 mmol) was dissolved in THF (50 mL) under an argonatmosphere at 0° C. Then tetrabutylammonium fluoride (0.252 g, 0.8 mmol)and a desired amount of porous activated soft carbon particles wereadded; the amount of porous activated soft carbon particles depending onthe final weight ratio between carbon and CuDEPP. After 40 min, thereaction mixture was poured into 50 mL MeOH. The precipitate wasfiltered and washed by 100 mL MeOH. The product was collected to yield adark purple solid, CuDEPP supported on graphene sheet surfaces.

Three types of cells were made, all having lithiated Si particles as theanode active material and 1 M of LiPF₆ in EC-PC (50/50) as theelectrolyte. One cell contains porous activated soft carbon particlesonly (no functionalized porphyrin) as the cathode active material. Asecond cell contains functionalized porphyrin as the cathode activematerial. A third cell contains the functionalized porphyrin/carbonhybrid particles as the cathode active material. The conventional slurrycoating and drying process was followed to make the cathode electrode.For instance, for the first cell, porous activated soft carbon particleswere mixed with NMP to form a slurry, which was then coated onto bothprimary surfaces of a sheet of Al foil (serving as a current collector).The cathode contains porous activated soft carbon particles (88% bywt.), 5% acetylene black as a conductive additive, and 7% PVDF binderresin. The anode (containing fully lithiated Si nano particles) was alsomade in a similar manner. An anode and a cathode are spaced by a porousseparator to form an electrochemical cell.

Example 9: Preparation of Single-Layer Graphene Sheets from Meso-CarbonMicro-Beads

Meso-carbon microbeads (MCMBs) were supplied from China Steel ChemicalCo., Kaohsiung, Taiwan. This material has a density of about 2.24 g/cm³with a median particle size of about 16 μm. MCMB (10 grams) wereintercalated with an acid solution (sulfuric acid, nitric acid, andpotassium permanganate at a ratio of 4:1:0.05) for 48-96 hours. Uponcompletion of the reaction, the mixture was poured into deionized waterand filtered. The intercalated MCMBs were repeatedly washed in a 5%solution of HCl to remove most of the sulphate ions. The sample was thenwashed repeatedly with deionized water until the pH of the filtrate wasno less than 4.5. The slurry was then subjected ultrasonication for10-100 minutes to produce GO suspensions. TEM and atomic forcemicroscopic studies indicate that most of the GO sheets weresingle-layer graphene when the oxidation treatment exceeded 72 hours,and 2- or 3-layer graphene when the oxidation time was from 48 to 72hours.

The GO sheets/carbon, in combinations with several different porphyrincompounds, were then made into pseudocapacitor cathodes. Eachpseudocapacitor cathode was then paired with a lithiated anode activematerial layer and a separator/electrolyte to form a cell. Several typesof cells, containing different anode and cathode material, were made andtested.

Example 10: Preparation of Pristine Graphene (0% Oxygen)

Recognizing the possibility of the high defect population in GO sheetsacting to reduce the conductivity of individual graphene plane, wedecided to study if the use of pristine graphene sheets (non-oxidizedand oxygen-free, non-halogenated and halogen-free, etc.) can lead to agraphene supercapacitor having a higher electrical conductivity andlower equivalent series resistance. Pristine graphene sheets wereproduced by using the direct ultrasonication process (also called theliquid-phase exfoliation process).

In a typical procedure, five grams of graphite flakes, ground toapproximately 20 μm or less in sizes, were dispersed in 1,000 mL ofdeionized water (containing 0.1% by weight of a dispersing agent, Zonyl®FSO from DuPont) to obtain a suspension. An ultrasonic energy level of85 W (Branson S450 Ultrasonicator) was used for exfoliation, separation,and size reduction of graphene sheets for a period of 15 minutes to 2hours. The resulting graphene sheets are pristine graphene that havenever been oxidized and are oxygen-free and relatively defect-free.There are essentially no other non-carbon elements. The pristinegraphene sheets, along with a selected carbon material, were then bondedwith several different porphyrin compounds to form differentpseudocapacitance cathodes.

Example 11: Preparation of Graphene Oxide (GO) Suspension from NaturalGraphite and of Subsequent GO-Supported Porphyrin Electrodes

Graphite oxide was prepared by oxidation of graphite flakes with anoxidizer liquid consisting of sulfuric acid, sodium nitrate, andpotassium permanganate at a ratio of 4:1:0.05 at 30° C. When naturalgraphite flakes (particle sizes of 14 μm) were immersed and dispersed inthe oxidizer mixture liquid for 48 hours, the suspension or slurryappears and remains optically opaque and dark. After 48 hours, thereacting mass was rinsed with water 3 times to adjust the pH value to atleast 3.0. A final amount of water was then added to prepare a series ofGO-water suspensions using ultrasonication. Some of these GO sheets,along with particles of a carbon material, were then dispersed in aliquid medium, along with a desired type of porphyrin material. Theresulting suspension containing porphyrin was then spray-dried to formisolated porphyrin-bonded carbon/graphene.

Example 12: Preparation of Graphene Fluoride (GF)

Several processes have been used by us to produce GF, but only oneprocess is herein described as an example. In a typical procedure,highly exfoliated graphite (HEG) was prepared from intercalated compoundC₂F.xClF₃. HEG was further fluorinated by vapors of chlorine trifluorideto yield fluorinated highly exfoliated graphite (FHEG). Pre-cooledTeflon reactor was filled with 20-30 mL of liquid pre-cooled ClF₃, thereactor was closed and cooled to liquid nitrogen temperature. Then, nomore than 1 g of HEG was put in a container with holes for ClF₃ gas toaccess and situated inside the reactor. In 7-10 days a gray-beigeproduct with approximate formula C₂F was formed.

Subsequently, a small amount of FHEG (approximately 0.5 mg), along witha desired amount of carbon particles, was mixed with 20-30 mL of anorganic solvent (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol,tert-butanol, or isoamyl alcohol) and subjected to an ultrasoundtreatment (280 W) for 30 min, leading to the formation of homogeneousyellowish dispersions. Five minutes of sonication was enough to obtain arelatively homogenous dispersion, but longer sonication lengths of timeensured better stability. During the sonication procedure, porphyrin wasadded for the preparation of the pseudocapacitance cathodes.

Example 13: Preparation of Nitrogenataed Graphene-Carbon/Porphyrin-BasedPseudocapacitor Cathodes

Graphene oxide (GO), synthesized in Example 2, was finely ground withdifferent proportions of urea and the pelletized mixture heated in amicrowave reactor (900 W) for 30 s. The product was washed several timeswith deionized water and vacuum dried. In this method graphene oxidegets simultaneously reduced and doped with nitrogen. The productsobtained with graphene/urea mass ratios of 1:0.5, 1:1 and 1:2,respectively and the nitrogen contents of these samples were 14.7, 18.2and 17.5 wt %, respectively as determined by elemental analysis. Thesenitrogenataed graphene sheets remain dispersible in water.

The polyporphyrin (TThPP) linked by 4-thiophenephenyl groups wassynthesized through an in situ chemical oxidative polymerization on thesurface of graphene sheets and/or particles of a carbon material. Theprocedure began with synthesis of 4-(Thiophen-2-yl)benzaldehyde, whichwas based on the following sequence. As an example, to a solution of4-bromobenzaldehyde (370 mg, 2.0 mmol) in dry THF (15 mL) was added thecatalyst Pd(PPh3)4 (115 mg, 0.1 mmol) at room temperature undernitrogen. After the mixture was stirred at room temperature for 0.5 h,thiophen-2-ylboronic acid (384 mg, 1.5 mmol) and 2 N aqueous K₂CO₃ (2mL, 4 mmol) were added into the reaction solution which was continuallystirred for 0.5 h at room temperature. Then, the reaction mixture wasrefluxed overnight. After the reaction, the solution was cooled down toroom temperature, and the solvent was removed. The residue was purifiedby silica gel column chromatography eluting with CH₂Cl₂/hexane (1:2) togive 4-(thiophen-2-yl)benzaldehyde (310 mg, 82%) as a yellow solid.

The synthesis of meso-tetrakis(4-thiophenephenyl)porphyrin (TThP) bondedon graphene surfaces were then conducted as follows: Into a 1000 mLthree-necked flask, 4-(thiophen-2-yl)-benzaldehyde (940 mg, 5 mmol),pyrrole (356 mg, 5 mmol) and 500 mL of CHCl₃ were added. After they werepumped with nitrogen for 15 min, 1.62 mmol of boron trifluoride diethyletherate (BFEE, 0.207 mL) was added into the solution. Then the mixturewas stirred at room temperature under nitrogen atmosphere. The reactionwas monitored by thin-layer chromatography (TLC). When the4-(thiophen-2-yl)benzaldehyde was consumed, 3.75 mmol of2,3-dichloro-5,6-dicyanol, 4-benzoquinone (DDQ, 0.851 g) and a desiredamount of nitrogenated graphene sheets were added, and the mixture wasallowed to stir for another 1 h. This amount of graphene sheets wasvaried to achieve a range of porphyrin/graphene ratios. Subsequently,the reaction was quenched by addition of 0.5 mL of triethylamine for 10min. After evaporation of the solvent, the crude product was purified bycolumn chromatography on silica gel using petroleum ether/CH₂Cl₂ (4:1)as the eluent. Then the product was filtered and washed with methanoluntil the filtrate became colorless to givemeso-tetrakis(4-thiophenephenyl)porphyrin (TThP) as a purple solidbonded on graphene surfaces. TThP is an example of porphyrin-basedpolymers.

Example 14: Preparation of Porphyrin Ni-Bonded Carbon Material

A porphyrin containing Ni at its center, dimesityl-substitutednorcorrole nickel(II) complex (NiNC), was synthesized according to theprocedure described in Hiroshi Shinokubo. Angew. Chem., (2013), 125:1400. doi: 10.1002/ange.201207020. However, before the final reactionwas allowed to proceed, a desired amount of activated needle coke wasadded into the reactor.

Pouch cells using NiNC-bonded needle coke as a cathode active material(90% NiNC-bonded needle coke and 10% PVDF as a resin binder) andlithiated SiO or SnO₂ anode were made and tested. In all cells, theseparator used was one sheet of micro-porous membrane (Celgard 2500).The current collector for the cathode was a piece of carbon-coatedaluminum foil and that for the anode was Cu foil. The electrolytesolution was 1 M LiPF₆ dissolved in a mixture of ethylene carbonate (EC)and dimethyl carbonate (DMC) with a 3:7 volume ratio. The separator waswetted by a minimum amount of electrolyte to reduce the backgroundcurrent. Cyclic voltammetry and galvanostatic measurements of thelithium cells were conducted using an Arbin 32-channelsupercapacitor-battery tester at room temperature (in some cases, at atemperature as low as −40° C. and as high as 60° C.).

Example 15: Details about Evaluation of Various Internal HybridElectrochemical Cells

In a conventional cell, an electrode (cathode or anode), is typicallycomposed of 85% of an electrode active material (e.g. graphene,activated carbon, or inorganic nano discs, etc.), 5% Super-P (acetyleneblack-based conductive additive), and 10% PTFE, which were mixed andcoated on Al foil. The thickness of electrode is around 100 m. For eachsample, both coin-size and pouch cells were assembled in a glove box.The capacity was measured with galvanostatic experiments using an ArbinSCTS electrochemical testing instrument. Cyclic voltammetry (CV) andelectrochemical impedance spectroscopy (EIS) were conducted on anelectrochemical workstation (CHI 660 System, USA).

Galvanostatic charge/discharge tests were conducted on the samples toevaluate the electrochemical performance. For the galvanostatic tests,the specific capacity (q) is calculated asq=I*t/m  (1)where I is the constant current in mA, t is the time in hours, and m isthe cathode active material mass in grams. With voltage V, the specificenergy (E) is calculated as,E=∫Vdq  (2)The specific power (P) can be calculated asP=(E/t)(W/kg)  (3)where t is the total charge or discharge step time in hours.The specific capacitance (C) of the cell is represented by the slope ateach point of the voltage vs. specific capacity plot,C=dq/dV  (4)For each sample, several current density (representing charge/dischargerates) were imposed to determine the electrochemical responses, allowingfor calculations of energy density and power density values required ofthe construction of a Ragone plot (power density vs. energy density).

FIG. 4 shows some representative charge-discharge curve of an internalhybrid cell, featuring a lithiated Si anode and s pseudocapacitancecathode containing CuDEPP-bonded porous activated soft carbon particles(prepared in Example 8). The shapes of these curves are characteristicof pseudocapacitance behaviors, rather than electric double layercapacitance (EDLC) or lithium ion-intercalation type battery behavior.The corresponding cyclic voltammetry diagrams further confirm the samebehaviors. It may be noted that, in contrast to the conventionallithium-ion capacitor, the instant internal hybrid cell does not have tobe limited to an operating voltage from 2.0 V to 4.3 V.

Shown in FIG. 5 are the charge storage capacity values (based on thetotal cathode active material weight) of two series of internal hybridcells each featuring a lithiated Si anode and a pseudocapacitancecathode containing CuDEPP-bonded porous activated soft carbon particlesor exfoliated graphite worms, and those of the cells containing, in thecathode, CuDEPP only or porous activated soft carbon particles only (orexfoliated graphite worms only) as the cathode active material. Thesedata have clearly exhibited surprising synergistic effects between aporphyrin molecule and a porous activated soft carbon particle or anexfoliated graphite worm flake. When implemented alone as a cathodeactive material, either CuDEPP or porous activated soft carbon particlesprovide very minimal charge storage capability. When combined to form aredox pair, the two species work together to provide exceptionally highcharge storage capacity, up to 278 mAh/g or 245 mAh/g (the sum of CuDEPPweight and carbon/graphite weight) between 1.5 V and 4.3 V.

The charge-discharge cycling data of a representative internal hybridcell are summarized in FIG. 6, which indicates that the internal cellexhibits not only a high specific capacity but also a stable cyclingbehavior. The cell suffers a capacitance loss of less than 1.24% after3,000 cycles, which is outstanding compared to conventionalpseudocapacitors or lithium-ion batteries.

FIG. 7 shows the Ragone plots of three types of electrochemical cellseach having a prelithiated SiO as the anode active material: (i) a cellusing activated needle coke as a cathode active material, (ii) a cellusing porphyrin-Ni (+10% carbon black as a conductive additive) as thecathode active material, and (iii) an internal hybrid cell usingporphyrin-Ni-bonded activated needle coke as a cathode active material(90% porphyrin-Ni-bonded activated needle coke and 10% PVDF as a resinbinder). These results again have demonstrated an unexpected synergisticeffect between porphyrin-Ni and activated needle coke when the pair ofporphyrin/activated needle coke materials is implemented as apseudocapacitance cathode.

Shown in FIG. 8 are the Ragone plots of three types of electrochemicalcells each having a prelithiated SnO₂ as the anode active material: (i)a cell using activated CNT as a cathode active material, (ii) a cellusing a functionalized porphyrin-Fe as the cathode active material, and(iii) an internal hybrid cell using functionalized porphyrin-Fe bondedactivated CNT as a cathode active material. These results again havedemonstrated an unexpected synergistic effect between a functionalizedporphyrin and activated CNT when this pair of porphyrin/carbon isimplemented as a pseudocapacitance cathode. Quite significantly, theenergy density of the presently invented internal hybrid cell is as highas 161 Wh/kg, which is comparable to those (150-220 Wh/kg) oflithium-ion batteries. A maximum power density of 13.5 kW/kg isdramatically higher than those (typically <0.5 kW/kg) of conventionallithium-ion batteries and even higher than those of supercapacitors.These results have demonstrated that the presently invented internalhybrid electrochemical cells have the best characteristics of bothlithium-ion batteries and supercapacitors.

We claim:
 1. An internal hybrid electrochemical cell comprising: (A) acathode comprising a cathode active material that contains a conductingcarbon material and a porphyrin compound, wherein said porphyrincompound is bonded to or supported by said carbon material to form aredox pair for pseudocapacitance and said carbon material is selectedfrom activated carbon, activated carbon black, expanded graphite flakes,exfoliated graphite worms, carbon nanotube, carbon nanofiber, carbonfiber, a combination thereof, or a combination thereof with graphene,wherein said porphyrin compound is bonded to graphene sheet surfaces ofsaid carbon material in a face-to-face manner; (B) a anode comprising aprelithiated anode active material selected from the group consisting of(a) lithiated silicon (Si), germanium (Ge), tin (Sn), lead (Pb),antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium (Ti),cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd), and mixturesthereof; (b) lithiated alloys or intermetallic compounds of Si, Ge, Sn,Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and their mixtures; (c)lithiated oxides, carbides, nitrides, sulfides, phosphides, selenides,tellurides, or antimonides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti,Co, Ni, Mn, Cd, and mixtures or composites thereof; (d) lithiatedgraphite and lithiated carbon materials; and (e) combinations thereof,and (C) a lithium-containing electrolyte in physical contact with theanode and the cathode; wherein said cathode active material has aspecific surface area no less than 100 m²/g which is in direct physicalcontact with said electrolyte.
 2. The internal hybrid electrochemicalcell of claim 1, wherein said anode comprises a prelithiated anodeactive material selected from lithiated Si, lithiated Ge, lithiated Sn,lithiated SiO, lithiated SnO₂, lithiated Co₃O₄, lithiated Mn₃O₄,lithiated Fe₃O₄, lithiated ZnMn₂O₄, or a combination thereof and saidanode does not contain lithium metal.
 3. The internal hybridelectrochemical cell of claim 1, wherein said lithiated graphite andlithiated carbon materials are selected from lithiated particles ofnatural graphite, artificial graphite, soft carbon, hard carbon, coke,carbon fibers, graphite fibers, carbon nanofibers, carbon nanotubes,carbon nanohorns, expanded graphite platelets, graphene sheets, or acombination thereof that have been pre-loaded with lithium, pre-reactedwith lithium, and/or pre-intercalated with lithium.
 4. The internalhybrid electrochemical cell of claim 1, wherein said porphyrin compoundis selected from porphyrin, porphyrin-copper, porphyrin-zinc,porphyrin-nickel, porphyrin-cobalt, porphyrin-manganese, porphyrin-iron,porphyrin-tin, porphyrin-cadmium, porphyrin-vanadium, polyporphyrin, achemical derivative of porphyrin, a functionalized porphyrin compound,or a combination thereof.
 5. The internal hybrid electrochemical cell ofclaim 1, wherein said porphyrin compound is selected from aporphyrin-transition metal complex.
 6. The internal hybridelectrochemical cell of claim 1, wherein said porphyrin compoundcontains a functionalized porphyrin compound having at least afunctional group attached to a porphyrin molecule, wherein saidfunctional group is selected from OY, NHY, O‥C—OY, P═C—NR′Y, O═C—SY,O═C—Y, —CR′1-OY, N′Y or C′Y, and Y is a functional group of a protein, apeptide, an amino acid, an enzyme, an antibody, a nucleotide, anoligonucleotide, an antigen, or an enzyme substrate, enzyme inhibitor orthe transition state analog of an enzyme substrate or is selected from aphenol group, R′—OH, R′—NR′₂, R′SH, R′CHO, R′CN, R′X, R′N⁺(R′)₃X⁻,R′SiR′₃, R′Si(—OR′—)_(y)R′_(3-y), R′Si(—O—SiR′₂—)OR′, R′—R″, R′—N—CO,(C₂H₄O—)_(w)H, (—C₃H₆O—)_(w)H, (—C₂H₄O)_(w)—R′, (C₃H₆O)_(w)—R′, R′, andw is an integer greater than one and less than
 200. 7. The internalhybrid electrochemical cell of claim 1, wherein said porphyrin compoundcontains a functionalized porphyrin compound having at least afunctional group attached to a porphyrin molecule, wherein saidfunctional group is selected from the group consisting of amidoamines,polyamides, aliphatic amines, modified aliphatic amines, cycloaliphaticamines, aromatic amines, anhydrides, ketimines, diethylenetriamine(DETA), triethylene-tetramine (TETA), tetraethylene-pentamine (TEPA),polyethylene polyamine, polyamine epoxy adduct, phenolic hardener,non-brominated curing agent, non-amine curatives, and combinationsthereof.
 8. The internal hybrid electrochemical cell of claim 1, whereinsaid porphyrin compound contains a functionalized porphyrin compoundhaving at least a functional group attached to a porphyrin molecule,wherein said functional group contains an azide or bi-radical compoundselected from the group consisting of 2-Azidoethanol,3-Azidopropan-1-amine, 4-(2-Azidoethoxy)-4-oxobutanoic acid,2-Azidoethyl-2-bromo-2-methylpropanoate, chlorocarbonate,azidocarbonate, dichlorocarbene, carbene, aryne, nitrene,(R-)-oxycarbonyl nitrenes, where R=any one of the following groups,

and combinations thereof.
 9. The internal hybrid electrochemical cell ofclaim 1, wherein said conductive carbon material forms a mesoporousstructure having meso-scaled pores of 2-50 nm and a specific surfacearea from 100 m²/g to 3,200 m²/g.
 10. The internal hybridelectrochemical cell of claim 1, wherein said activated carbon isselected from chemically etched or expanded soft carbon, chemicallyetched or expanded hard carbon, exfoliated activated carbon, chemicallyetched multi-walled carbon nanotube, nitrogen-doped carbon nanotube,boron-doped carbon nanotube, chemically doped carbon nanotube,ion-implanted carbon nanotube, chemically treated multi-walled carbonnanotube with an inter-planar separation no less than 0.4 nm, chemicallyexpanded carbon nanofiber, activated carbon fiber, activated graphitefiber, activated carbonized polymer fiber, activated coke, activatedpitch, activated asphalt, activated mesophase carbon, activatedmesoporous carbon, activated electrospun conductive nanofiber, or acombination thereof.
 11. The internal hybrid electrochemical cell ofclaim 1, wherein said graphene sheets comprise single-layer or few-layergraphene, containing up to 10 graphene planes, selected from pristinegraphene, graphene oxide, reduced graphene oxide, halogenated graphene,hydrogenated graphene, nitrogenated graphene, doped graphene, chemicallyfunctionalized graphene, or a combination thereof.
 12. The internalhybrid electrochemical cell of claim 1, wherein said lithium metal orlithium metal alloy is in a form of metal foil, film, particles, chips,or filaments and wherein said metal alloy contains no less than 80% byweight of lithium.
 13. The internal hybrid electrochemical cell of claim1, wherein said anode active material contains prelithiated particles ofSi, Ge, SiO, Sn, SnO₂, or a combination thereof.
 14. The internal hybridelectrochemical cell of claim 1, wherein said cathode further contains aresin binder that bonds particles of said cathode active materialtogether.
 15. The internal hybrid electrochemical cell of claim 1,wherein at least one of the anode and the cathode contains a currentcollector that is a porous, electrically conductive material selectedfrom metal foam, metal web or screen, perforated metal sheet, metalfiber mat, metal nanowire mat, porous conductive polymer film,conductive polymer nanofiber mat or paper, conductive polymer foam,carbon foam, carbon aerogel, carbon xerogel, graphene foam, grapheneoxide foam, reduced graphene oxide foam, carbon fiber paper, graphenepaper, graphene oxide paper, reduced graphene oxide paper, carbonnanofiber paper, carbon nanotube paper, or a combination thereof. 16.The internal hybrid electrochemical cell of claim 1, wherein said anodeactive material contains prelithiated particles of Si, Ge, SiO, Sn,SnO₂, or a combination thereof and said prelithiated particles reside inpores of a porous, electrically conductive material selected from metalfoam, metal web or screen, perforated metal sheet, metal fiber mat,metal nanowire mat, porous conductive polymer film, conductive polymernanofiber mat or paper, conductive polymer foam, carbon foam, carbonaerogel, carbon xerogel, graphene foam, graphene oxide foam, reducedgraphene oxide foam, carbon fiber paper, graphene paper, graphene oxidepaper, reduced graphene oxide paper, carbon nanofiber paper, carbonnanotube paper, or a combination thereof.
 17. The internal hybridelectrochemical cell of claim 1, wherein the electrolyte is organicliquid electrolyte, ionic liquid electrolyte, or gel electrolytecontaining an amount of lithium ions when said cell is made.
 18. Anenergy storage device comprising at least two internal hybridelectrochemical cells of claim 1 connected in series or in parallel. 19.An energy device comprising at least one internal hybrid electrochemicalcell of claim 1, which is electrically connected to an electrochemicalcell in series or in parallel.
 20. An internal hybrid electrochemicalcell comprising: (A) a cathode comprising a cathode active material thatcontains a graphene material and a porphyrin compound, wherein saidporphyrin compound is bonded to or supported by said graphene materialto form graphene-porphyrin compound hybrid sheets which form a redoxpair for pseudocapacitance, wherein said graphene material is in anamount of from 0.5% to 99% by weight based on the total weight of saidgraphene material and said porphyrin compound combined; (B) a anodecomprising a prelithiated anode active material selected from the groupconsisting of (a) lithiated silicon (Si), germanium (Ge), tin (Sn), lead(Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium(Ti), cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd), andmixtures thereof; (b) lithiated alloys or intermetallic compounds of Si,Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and their mixtures; (c)lithiated oxides, carbides, nitrides, sulfides, phosphides, selenides,tellurides, or antimonides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti,Co, Ni, Mn, Cd, and mixtures or composites thereof; (d) lithiatedgraphite and lithiated carbon materials; and (e) combinations thereof,and a lithium-containing electrolyte in physical contact with the anodeand the cathode; wherein said cathode active material has a specificsurface area no less than 100 m²/g which is in direct physical contactwith said electrolyte.